iojs.1

.TH IO.JS "1" "2010" "" ""


.SH "NAME"
iojs \- Server-side JavaScript

.SH SYNOPSIS


.B iojs
[
.B \-v
]
[
.B \-\-debug
|
.B \-\-debug-brk
]
[
.B \-\-v8-options
]
.br
     [
.B \-e
.I command
|
.I script.js
]
[
.I arguments
]

Execute without arguments to start the REPL.


.SH DESCRIPTION

io.js is a set of libraries for javascript which allows
it to be used outside of the browser. It is primarily
focused on creating simple, easy to build network clients
and servers.


.SH OPTIONS

  -v, --version          print iojs's version

  -e, --eval script      evaluate script

  -p, --print            print result of --eval

  -i, --interactive      always enter the REPL even if stdin
                         does not appear to be a terminal

  -r, --require          module to preload at startup

  --no-deprecation       silence deprecation warnings

  --trace-deprecation    show stack traces on deprecations

  --throw-deprecation    throw errors on deprecations

  --v8-options           print v8 command line options

  --max-stack-size=val   set max v8 stack size (bytes)


.SH ENVIRONMENT VARIABLES

.IP NODE_PATH
\':\'\-separated list of directories prefixed to the module search path.

.IP NODE_DISABLE_COLORS
If set to 1 then colors will not be used in the REPL.

.SH V8 OPTIONS

  --use_strict (enforce strict mode)
        type: bool  default: false
  --es_staging (enable all completed harmony features)
        type: bool  default: false
  --harmony (enable all completed harmony features)
        type: bool  default: false
  --harmony_shipping (enable all shipped harmony fetaures)
        type: bool  default: true
  --harmony_modules (enable "harmony modules (implies block scoping)" (in progress))
        type: bool  default: false
  --harmony_arrays (enable "harmony array methods" (in progress))
        type: bool  default: false
  --harmony_array_includes (enable "harmony Array.prototype.includes" (in progress))
        type: bool  default: false
  --harmony_regexps (enable "harmony regular expression extensions" (in progress))
        type: bool  default: false
  --harmony_arrow_functions (enable "harmony arrow functions" (in progress))
        type: bool  default: false
  --harmony_proxies (enable "harmony proxies" (in progress))
        type: bool  default: false
  --harmony_sloppy (enable "harmony features in sloppy mode" (in progress))
        type: bool  default: false
  --harmony_unicode (enable "harmony unicode escapes" (in progress))
        type: bool  default: false
  --harmony_tostring (enable "harmony toString")
        type: bool  default: false
  --harmony_numeric_literals (enable "harmony numeric literals")
        type: bool  default: true
  --harmony_strings (enable "harmony string methods")
        type: bool  default: true
  --harmony_scoping (enable "harmony block scoping")
        type: bool  default: true
  --harmony_classes (enable "harmony classes (implies block scoping & object literal extension)")
        type: bool  default: true
  --harmony_object_literals (enable "harmony object literal extensions")
        type: bool  default: true
  --harmony_templates (enable "harmony template literals")
        type: bool  default: true
  --compiled_keyed_generic_loads (use optimizing compiler to generate keyed generic load stubs)
        type: bool  default: false
  --pretenuring_call_new (pretenure call new)
        type: bool  default: false
  --allocation_site_pretenuring (pretenure with allocation sites)
        type: bool  default: true
  --trace_pretenuring (trace pretenuring decisions of HAllocate instructions)
        type: bool  default: false
  --trace_pretenuring_statistics (trace allocation site pretenuring statistics)
        type: bool  default: false
  --track_fields (track fields with only smi values)
        type: bool  default: true
  --track_double_fields (track fields with double values)
        type: bool  default: true
  --track_heap_object_fields (track fields with heap values)
        type: bool  default: true
  --track_computed_fields (track computed boilerplate fields)
        type: bool  default: true
  --track_field_types (track field types)
        type: bool  default: true
  --smi_binop (support smi representation in binary operations)
        type: bool  default: true
  --vector_ics (support vector-based ics)
        type: bool  default: false
  --optimize_for_size (Enables optimizations which favor memory size over execution speed.)
        type: bool  default: false
  --unbox_double_arrays (automatically unbox arrays of doubles)
        type: bool  default: true
  --string_slices (use string slices)
        type: bool  default: true
  --crankshaft (use crankshaft)
        type: bool  default: true
  --hydrogen_filter (optimization filter)
        type: string  default: *
  --use_gvn (use hydrogen global value numbering)
        type: bool  default: true
  --gvn_iterations (maximum number of GVN fix-point iterations)
        type: int  default: 3
  --use_canonicalizing (use hydrogen instruction canonicalizing)
        type: bool  default: true
  --use_inlining (use function inlining)
        type: bool  default: true
  --use_escape_analysis (use hydrogen escape analysis)
        type: bool  default: true
  --use_allocation_folding (use allocation folding)
        type: bool  default: true
  --use_local_allocation_folding (only fold in basic blocks)
        type: bool  default: false
  --use_write_barrier_elimination (eliminate write barriers targeting allocations in optimized code)
        type: bool  default: true
  --max_inlining_levels (maximum number of inlining levels)
        type: int  default: 5
  --max_inlined_source_size (maximum source size in bytes considered for a single inlining)
        type: int  default: 600
  --max_inlined_nodes (maximum number of AST nodes considered for a single inlining)
        type: int  default: 196
  --max_inlined_nodes_cumulative (maximum cumulative number of AST nodes considered for inlining)
        type: int  default: 400
  --loop_invariant_code_motion (loop invariant code motion)
        type: bool  default: true
  --fast_math (faster (but maybe less accurate) math functions)
        type: bool  default: true
  --collect_megamorphic_maps_from_stub_cache (crankshaft harvests type feedback from stub cache)
        type: bool  default: true
  --hydrogen_stats (print statistics for hydrogen)
        type: bool  default: false
  --trace_check_elimination (trace check elimination phase)
        type: bool  default: false
  --trace_hydrogen (trace generated hydrogen to file)
        type: bool  default: false
  --trace_hydrogen_filter (hydrogen tracing filter)
        type: string  default: *
  --trace_hydrogen_stubs (trace generated hydrogen for stubs)
        type: bool  default: false
  --trace_hydrogen_file (trace hydrogen to given file name)
        type: string  default: NULL
  --trace_phase (trace generated IR for specified phases)
        type: string  default: HLZ
  --trace_inlining (trace inlining decisions)
        type: bool  default: false
  --trace_load_elimination (trace load elimination)
        type: bool  default: false
  --trace_store_elimination (trace store elimination)
        type: bool  default: false
  --trace_alloc (trace register allocator)
        type: bool  default: false
  --trace_all_uses (trace all use positions)
        type: bool  default: false
  --trace_range (trace range analysis)
        type: bool  default: false
  --trace_gvn (trace global value numbering)
        type: bool  default: false
  --trace_representation (trace representation types)
        type: bool  default: false
  --trace_removable_simulates (trace removable simulates)
        type: bool  default: false
  --trace_escape_analysis (trace hydrogen escape analysis)
        type: bool  default: false
  --trace_allocation_folding (trace allocation folding)
        type: bool  default: false
  --trace_track_allocation_sites (trace the tracking of allocation sites)
        type: bool  default: false
  --trace_migration (trace object migration)
        type: bool  default: false
  --trace_generalization (trace map generalization)
        type: bool  default: false
  --stress_pointer_maps (pointer map for every instruction)
        type: bool  default: false
  --stress_environments (environment for every instruction)
        type: bool  default: false
  --deopt_every_n_times (deoptimize every n times a deopt point is passed)
        type: int  default: 0
  --deopt_every_n_garbage_collections (deoptimize every n garbage collections)
        type: int  default: 0
  --print_deopt_stress (print number of possible deopt points)
        type: bool  default: false
  --trap_on_deopt (put a break point before deoptimizing)
        type: bool  default: false
  --trap_on_stub_deopt (put a break point before deoptimizing a stub)
        type: bool  default: false
  --deoptimize_uncommon_cases (deoptimize uncommon cases)
        type: bool  default: true
  --polymorphic_inlining (polymorphic inlining)
        type: bool  default: true
  --use_osr (use on-stack replacement)
        type: bool  default: true
  --array_bounds_checks_elimination (perform array bounds checks elimination)
        type: bool  default: true
  --trace_bce (trace array bounds check elimination)
        type: bool  default: false
  --array_bounds_checks_hoisting (perform array bounds checks hoisting)
        type: bool  default: false
  --array_index_dehoisting (perform array index dehoisting)
        type: bool  default: true
  --analyze_environment_liveness (analyze liveness of environment slots and zap dead values)
        type: bool  default: true
  --load_elimination (use load elimination)
        type: bool  default: true
  --check_elimination (use check elimination)
        type: bool  default: true
  --store_elimination (use store elimination)
        type: bool  default: false
  --dead_code_elimination (use dead code elimination)
        type: bool  default: true
  --fold_constants (use constant folding)
        type: bool  default: true
  --trace_dead_code_elimination (trace dead code elimination)
        type: bool  default: false
  --unreachable_code_elimination (eliminate unreachable code)
        type: bool  default: true
  --trace_osr (trace on-stack replacement)
        type: bool  default: false
  --stress_runs (number of stress runs)
        type: int  default: 0
  --lookup_sample_by_shared (when picking a function to optimize, watch for shared function info, not JSFunction itself)
        type: bool  default: true
  --cache_optimized_code (cache optimized code for closures)
        type: bool  default: true
  --flush_optimized_code_cache (flushes the cache of optimized code for closures on every GC)
        type: bool  default: true
  --inline_construct (inline constructor calls)
        type: bool  default: true
  --inline_arguments (inline functions with arguments object)
        type: bool  default: true
  --inline_accessors (inline JavaScript accessors)
        type: bool  default: true
  --escape_analysis_iterations (maximum number of escape analysis fix-point iterations)
        type: int  default: 2
  --optimize_for_in (optimize functions containing for-in loops)
        type: bool  default: true
  --concurrent_recompilation (optimizing hot functions asynchronously on a separate thread)
        type: bool  default: true
  --job_based_recompilation (post tasks to v8::Platform instead of using a thread for concurrent recompilation)
        type: bool  default: false
  --trace_concurrent_recompilation (track concurrent recompilation)
        type: bool  default: false
  --concurrent_recompilation_queue_length (the length of the concurrent compilation queue)
        type: int  default: 8
  --concurrent_recompilation_delay (artificial compilation delay in ms)
        type: int  default: 0
  --block_concurrent_recompilation (block queued jobs until released)
        type: bool  default: false
  --concurrent_osr (concurrent on-stack replacement)
        type: bool  default: true
  --omit_map_checks_for_leaf_maps (do not emit check maps for constant values that have a leaf map, deoptimize the optimized code if the layout of the maps changes.)
        type: bool  default: true
  --turbo_filter (optimization filter for TurboFan compiler)
        type: string  default: ~
  --trace_turbo (trace generated TurboFan IR)
        type: bool  default: false
  --trace_turbo_graph (trace generated TurboFan graphs)
        type: bool  default: false
  --trace_turbo_cfg_file (trace turbo cfg graph (for C1 visualizer) to a given file name)
        type: string  default: NULL
  --trace_turbo_types (trace TurboFan's types)
        type: bool  default: true
  --trace_turbo_scheduler (trace TurboFan's scheduler)
        type: bool  default: false
  --trace_turbo_reduction (trace TurboFan's various reducers)
        type: bool  default: false
  --trace_turbo_jt (trace TurboFan's jump threading)
        type: bool  default: false
  --turbo_asm (enable TurboFan for asm.js code)
        type: bool  default: true
  --turbo_verify (verify TurboFan graphs at each phase)
        type: bool  default: false
  --turbo_stats (print TurboFan statistics)
        type: bool  default: false
  --turbo_types (use typed lowering in TurboFan)
        type: bool  default: true
  --turbo_source_positions (track source code positions when building TurboFan IR)
        type: bool  default: false
  --context_specialization (enable context specialization in TurboFan)
        type: bool  default: false
  --turbo_deoptimization (enable deoptimization in TurboFan)
        type: bool  default: false
  --turbo_inlining (enable inlining in TurboFan)
        type: bool  default: false
  --turbo_inlining_intrinsics (enable inlining of intrinsics in TurboFan)
        type: bool  default: false
  --trace_turbo_inlining (trace TurboFan inlining)
        type: bool  default: false
  --loop_assignment_analysis (perform loop assignment analysis)
        type: bool  default: true
  --turbo_profiling (enable profiling in TurboFan)
        type: bool  default: false
  --turbo_reuse_spill_slots (reuse spill slots in TurboFan)
        type: bool  default: true
  --turbo_delay_ssa_decon (delay ssa deconstruction in TurboFan register allocator)
        type: bool  default: false
  --turbo_move_optimization (optimize gap moves in TurboFan)
        type: bool  default: true
  --turbo_jt (enable jump threading)
        type: bool  default: true
  --typed_array_max_size_in_heap (threshold for in-heap typed array)
        type: int  default: 64
  --frame_count (number of stack frames inspected by the profiler)
        type: int  default: 1
  --interrupt_budget (execution budget before interrupt is triggered)
        type: int  default: 6144
  --type_info_threshold (percentage of ICs that must have type info to allow optimization)
        type: int  default: 25
  --generic_ic_threshold (max percentage of megamorphic/generic ICs to allow optimization)
        type: int  default: 30
  --self_opt_count (call count before self-optimization)
        type: int  default: 130
  --trace_opt_verbose (extra verbose compilation tracing)
        type: bool  default: false
  --debug_code (generate extra code (assertions) for debugging)
        type: bool  default: false
  --code_comments (emit comments in code disassembly)
        type: bool  default: false
  --enable_sse3 (enable use of SSE3 instructions if available)
        type: bool  default: true
  --enable_sse4_1 (enable use of SSE4.1 instructions if available)
        type: bool  default: true
  --enable_sahf (enable use of SAHF instruction if available (X64 only))
        type: bool  default: true
  --enable_avx (enable use of AVX instructions if available)
        type: bool  default: true
  --enable_fma3 (enable use of FMA3 instructions if available)
        type: bool  default: true
  --enable_vfp3 (enable use of VFP3 instructions if available)
        type: bool  default: true
  --enable_armv7 (enable use of ARMv7 instructions if available (ARM only))
        type: bool  default: true
  --enable_armv8 (enable use of ARMv8 instructions if available (ARM 32-bit only))
        type: bool  default: true
  --enable_neon (enable use of NEON instructions if available (ARM only))
        type: bool  default: true
  --enable_sudiv (enable use of SDIV and UDIV instructions if available (ARM only))
        type: bool  default: true
  --enable_mls (enable use of MLS instructions if available (ARM only))
        type: bool  default: true
  --enable_movw_movt (enable loading 32-bit constant by means of movw/movt instruction pairs (ARM only))
        type: bool  default: false
  --enable_unaligned_accesses (enable unaligned accesses for ARMv7 (ARM only))
        type: bool  default: true
  --enable_32dregs (enable use of d16-d31 registers on ARM - this requires VFP3)
        type: bool  default: true
  --enable_vldr_imm (enable use of constant pools for double immediate (ARM only))
        type: bool  default: false
  --force_long_branches (force all emitted branches to be in long mode (MIPS only))
        type: bool  default: false
  --expose_natives_as (expose natives in global object)
        type: string  default: NULL
  --expose_debug_as (expose debug in global object)
        type: string  default: NULL
  --expose_free_buffer (expose freeBuffer extension)
        type: bool  default: false
  --expose_gc (expose gc extension)
        type: bool  default: false
  --expose_gc_as (expose gc extension under the specified name)
        type: string  default: NULL
  --expose_externalize_string (expose externalize string extension)
        type: bool  default: false
  --expose_trigger_failure (expose trigger-failure extension)
        type: bool  default: false
  --stack_trace_limit (number of stack frames to capture)
        type: int  default: 10
  --builtins_in_stack_traces (show built-in functions in stack traces)
        type: bool  default: false
  --disable_native_files (disable builtin natives files)
        type: bool  default: false
  --inline_new (use fast inline allocation)
        type: bool  default: true
  --trace_codegen (print name of functions for which code is generated)
        type: bool  default: false
  --trace (trace function calls)
        type: bool  default: false
  --mask_constants_with_cookie (use random jit cookie to mask large constants)
        type: bool  default: true
  --lazy (use lazy compilation)
        type: bool  default: true
  --trace_opt (trace lazy optimization)
        type: bool  default: false
  --trace_opt_stats (trace lazy optimization statistics)
        type: bool  default: false
  --opt (use adaptive optimizations)
        type: bool  default: true
  --always_opt (always try to optimize functions)
        type: bool  default: false
  --always_osr (always try to OSR functions)
        type: bool  default: false
  --prepare_always_opt (prepare for turning on always opt)
        type: bool  default: false
  --trace_deopt (trace optimize function deoptimization)
        type: bool  default: false
  --trace_stub_failures (trace deoptimization of generated code stubs)
        type: bool  default: false
  --serialize_toplevel (enable caching of toplevel scripts)
        type: bool  default: true
  --serialize_inner (enable caching of inner functions)
        type: bool  default: false
  --trace_serializer (print code serializer trace)
        type: bool  default: false
  --min_preparse_length (minimum length for automatic enable preparsing)
        type: int  default: 1024
  --max_opt_count (maximum number of optimization attempts before giving up.)
        type: int  default: 10
  --compilation_cache (enable compilation cache)
        type: bool  default: true
  --cache_prototype_transitions (cache prototype transitions)
        type: bool  default: true
  --cpu_profiler_sampling_interval (CPU profiler sampling interval in microseconds)
        type: int  default: 1000
  --trace_debug_json (trace debugging JSON request/response)
        type: bool  default: false
  --trace_js_array_abuse (trace out-of-bounds accesses to JS arrays)
        type: bool  default: false
  --trace_external_array_abuse (trace out-of-bounds-accesses to external arrays)
        type: bool  default: false
  --trace_array_abuse (trace out-of-bounds accesses to all arrays)
        type: bool  default: false
  --enable_liveedit (enable liveedit experimental feature)
        type: bool  default: true
  --hard_abort (abort by crashing)
        type: bool  default: true
  --stack_size (default size of stack region v8 is allowed to use (in kBytes))
        type: int  default: 984
  --max_stack_trace_source_length (maximum length of function source code printed in a stack trace.)
        type: int  default: 300
  --always_inline_smi_code (always inline smi code in non-opt code)
        type: bool  default: false
  --min_semi_space_size (min size of a semi-space (in MBytes), the new space consists of twosemi-spaces)
        type: int  default: 0
  --target_semi_space_size (target size of a semi-space (in MBytes) before triggering a GC)
        type: int  default: 0
  --max_semi_space_size (max size of a semi-space (in MBytes), the new space consists of twosemi-spaces)
        type: int  default: 0
  --semi_space_growth_factor (factor by which to grow the new space)
        type: int  default: 2
  --experimental_new_space_growth_heuristic (Grow the new space based on the percentage of survivors instead of their absolute value.)
        type: bool  default: false
  --max_old_space_size (max size of the old space (in Mbytes))
        type: int  default: 0
  --initial_old_space_size (initial old space size (in Mbytes))
        type: int  default: 0
  --max_executable_size (max size of executable memory (in Mbytes))
        type: int  default: 0
  --gc_global (always perform global GCs)
        type: bool  default: false
  --gc_interval (garbage collect after <n> allocations)
        type: int  default: -1
  --trace_gc (print one trace line following each garbage collection)
        type: bool  default: false
  --trace_gc_nvp (print one detailed trace line in name=value format after each garbage collection)
        type: bool  default: false
  --trace_gc_ignore_scavenger (do not print trace line after scavenger collection)
        type: bool  default: false
  --trace_idle_notification (print one trace line following each idle notification)
        type: bool  default: false
  --trace_idle_notification_verbose (prints the heap state used by the idle notification)
        type: bool  default: false
  --print_cumulative_gc_stat (print cumulative GC statistics in name=value format on exit)
        type: bool  default: false
  --print_max_heap_committed (print statistics of the maximum memory committed for the heap in name=value format on exit)
        type: bool  default: false
  --trace_gc_verbose (print more details following each garbage collection)
        type: bool  default: false
  --trace_fragmentation (report fragmentation for old pointer and data pages)
        type: bool  default: false
  --collect_maps (garbage collect maps from which no objects can be reached)
        type: bool  default: true
  --weak_embedded_maps_in_optimized_code (make maps embedded in optimized code weak)
        type: bool  default: true
  --weak_embedded_objects_in_optimized_code (make objects embedded in optimized code weak)
        type: bool  default: true
  --flush_code (flush code that we expect not to use again (during full gc))
        type: bool  default: true
  --flush_code_incrementally (flush code that we expect not to use again (incrementally))
        type: bool  default: true
  --trace_code_flushing (trace code flushing progress)
        type: bool  default: false
  --age_code (track un-executed functions to age code and flush only old code (required for code flushing))
        type: bool  default: true
  --incremental_marking (use incremental marking)
        type: bool  default: true
  --incremental_marking_steps (do incremental marking steps)
        type: bool  default: true
  --concurrent_sweeping (use concurrent sweeping)
        type: bool  default: true
  --trace_incremental_marking (trace progress of the incremental marking)
        type: bool  default: false
  --track_gc_object_stats (track object counts and memory usage)
        type: bool  default: false
  --heap_profiler_trace_objects (Dump heap object allocations/movements/size_updates)
        type: bool  default: false
  --use_idle_notification (Use idle notification to reduce memory footprint.)
        type: bool  default: true
  --use_ic (use inline caching)
        type: bool  default: true
  --trace_ic (trace inline cache state transitions)
        type: bool  default: false
  --native_code_counters (generate extra code for manipulating stats counters)
        type: bool  default: false
  --always_compact (Perform compaction on every full GC)
        type: bool  default: false
  --never_compact (Never perform compaction on full GC - testing only)
        type: bool  default: false
  --compact_code_space (Compact code space on full non-incremental collections)
        type: bool  default: true
  --incremental_code_compaction (Compact code space on full incremental collections)
        type: bool  default: true
  --cleanup_code_caches_at_gc (Flush inline caches prior to mark compact collection and flush code caches in maps during mark compact cycle.)
        type: bool  default: true
  --use_marking_progress_bar (Use a progress bar to scan large objects in increments when incremental marking is active.)
        type: bool  default: true
  --zap_code_space (Zap free memory in code space with 0xCC while sweeping.)
        type: bool  default: true
  --random_seed (Default seed for initializing random generator (0, the default, means to use system random).)
        type: int  default: 0
  --trace_weak_arrays (trace WeakFixedArray usage)
        type: bool  default: false
  --track_prototype_users (keep track of which maps refer to a given prototype object)
        type: bool  default: false
  --use_verbose_printer (allows verbose printing)
        type: bool  default: true
  --allow_natives_syntax (allow natives syntax)
        type: bool  default: false
  --trace_parse (trace parsing and preparsing)
        type: bool  default: false
  --trace_sim (Trace simulator execution)
        type: bool  default: false
  --debug_sim (Enable debugging the simulator)
        type: bool  default: false
  --check_icache (Check icache flushes in ARM and MIPS simulator)
        type: bool  default: false
  --stop_sim_at (Simulator stop after x number of instructions)
        type: int  default: 0
  --sim_stack_alignment (Stack alingment in bytes in simulator (4 or 8, 8 is default))
        type: int  default: 8
  --sim_stack_size (Stack size of the ARM64 and MIPS64 simulator in kBytes (default is 2 MB))
        type: int  default: 2048
  --log_regs_modified (When logging register values, only print modified registers.)
        type: bool  default: true
  --log_colour (When logging, try to use coloured output.)
        type: bool  default: true
  --ignore_asm_unimplemented_break (Don't break for ASM_UNIMPLEMENTED_BREAK macros.)
        type: bool  default: false
  --trace_sim_messages (Trace simulator debug messages. Implied by --trace-sim.)
        type: bool  default: false
  --stack_trace_on_illegal (print stack trace when an illegal exception is thrown)
        type: bool  default: false
  --abort_on_uncaught_exception (abort program (dump core) when an uncaught exception is thrown)
        type: bool  default: false
  --randomize_hashes (randomize hashes to avoid predictable hash collisions (with snapshots this option cannot override the baked-in seed))
        type: bool  default: true
  --hash_seed (Fixed seed to use to hash property keys (0 means random)(with snapshots this option cannot override the baked-in seed))
        type: int  default: 0
  --profile_deserialization (Print the time it takes to deserialize the snapshot.)
        type: bool  default: false
  --regexp_optimization (generate optimized regexp code)
        type: bool  default: true
  --testing_bool_flag (testing_bool_flag)
        type: bool  default: true
  --testing_maybe_bool_flag (testing_maybe_bool_flag)
        type: maybe_bool  default: unset
  --testing_int_flag (testing_int_flag)
        type: int  default: 13
  --testing_float_flag (float-flag)
        type: float  default: 2.5
  --testing_string_flag (string-flag)
        type: string  default: Hello, world!
  --testing_prng_seed (Seed used for threading test randomness)
        type: int  default: 42
  --testing_serialization_file (file in which to serialize heap)
        type: string  default: /tmp/serdes
  --startup_blob (Write V8 startup blob file. (mksnapshot only))
        type: string  default: NULL
  --profile_hydrogen_code_stub_compilation (Print the time it takes to lazily compile hydrogen code stubs.)
        type: bool  default: false
  --predictable (enable predictable mode)
        type: bool  default: false
  --help (Print usage message, including flags, on console)
        type: bool  default: true
  --dump_counters (Dump counters on exit)
        type: bool  default: false
  --debugger (Enable JavaScript debugger)
        type: bool  default: false
  --map_counters (Map counters to a file)
        type: string  default:
  --js_arguments (Pass all remaining arguments to the script. Alias for "--".)
        type: arguments  default:
  --gdbjit (enable GDBJIT interface (disables compacting GC))
        type: bool  default: false
  --gdbjit_full (enable GDBJIT interface for all code objects)
        type: bool  default: false
  --gdbjit_dump (dump elf objects with debug info to disk)
        type: bool  default: false
  --gdbjit_dump_filter (dump only objects containing this substring)
        type: string  default:
  --force_marking_deque_overflows (force overflows of marking deque by reducing it's size to 64 words)
        type: bool  default: false
  --stress_compaction (stress the GC compactor to flush out bugs (implies --force_marking_deque_overflows))
        type: bool  default: false
  --log (Minimal logging (no API, code, GC, suspect, or handles samples).)
        type: bool  default: false
  --log_all (Log all events to the log file.)
        type: bool  default: false
  --log_api (Log API events to the log file.)
        type: bool  default: false
  --log_code (Log code events to the log file without profiling.)
        type: bool  default: false
  --log_gc (Log heap samples on garbage collection for the hp2ps tool.)
        type: bool  default: false
  --log_handles (Log global handle events.)
        type: bool  default: false
  --log_snapshot_positions (log positions of (de)serialized objects in the snapshot.)
        type: bool  default: false
  --log_suspect (Log suspect operations.)
        type: bool  default: false
  --prof (Log statistical profiling information (implies --log-code).)
        type: bool  default: false
  --prof_browser_mode (Used with --prof, turns on browser-compatible mode for profiling.)
        type: bool  default: true
  --log_regexp (Log regular expression execution.)
        type: bool  default: false
  --logfile (Specify the name of the log file.)
        type: string  default: v8.log
  --logfile_per_isolate (Separate log files for each isolate.)
        type: bool  default: true
  --ll_prof (Enable low-level linux profiler.)
        type: bool  default: false
  --perf_basic_prof (Enable perf linux profiler (basic support).)
        type: bool  default: false
  --perf_jit_prof (Enable perf linux profiler (experimental annotate support).)
        type: bool  default: false
  --gc_fake_mmap (Specify the name of the file for fake gc mmap used in ll_prof)
        type: string  default: /tmp/__v8_gc__
  --log_internal_timer_events (Time internal events.)
        type: bool  default: false
  --log_timer_events (Time events including external callbacks.)
        type: bool  default: false
  --log_instruction_stats (Log AArch64 instruction statistics.)
        type: bool  default: false
  --log_instruction_file (AArch64 instruction statistics log file.)
        type: string  default: arm64_inst.csv
  --log_instruction_period (AArch64 instruction statistics logging period.)
        type: int  default: 4194304
  --redirect_code_traces (output deopt information and disassembly into file code-<pid>-<isolate id>.asm)
        type: bool  default: false
  --redirect_code_traces_to (output deopt information and disassembly into the given file)
        type: string  default: NULL
  --hydrogen_track_positions (track source code positions when building IR)
        type: bool  default: false
  --trace_elements_transitions (trace elements transitions)
        type: bool  default: false
  --trace_creation_allocation_sites (trace the creation of allocation sites)
        type: bool  default: false
  --print_code_stubs (print code stubs)
        type: bool  default: false
  --test_secondary_stub_cache (test secondary stub cache by disabling the primary one)
        type: bool  default: false
  --test_primary_stub_cache (test primary stub cache by disabling the secondary one)
        type: bool  default: false
  --print_code (print generated code)
        type: bool  default: false
  --print_opt_code (print optimized code)
        type: bool  default: false
  --print_unopt_code (print unoptimized code before printing optimized code based on it)
        type: bool  default: false
  --print_code_verbose (print more information for code)
        type: bool  default: false
  --print_builtin_code (print generated code for builtins)
        type: bool  default: false
  --sodium (print generated code output suitable for use with the Sodium code viewer)
        type: bool  default: false
  --print_all_code (enable all flags related to printing code)
        type: bool  default: false

.SH RESOURCES AND DOCUMENTATION

See the website for documentation http://iojs.org/

Mailing list: http://groups.google.com/group/nodejs

IRC: irc.freenode.net #io.js