js
Provides functions for introspecting and configuring the QuickJS runtime engine. Includes debug info, memory usage, GC controls, code evaluation, etc.
cycle_hook(callback) function
or undefined to remove the callback.
Register or remove a hook function that QuickJS calls once per execution cycle. If the callback is set, it receives a single argument (an optional object/value describing the cycle). If callback is undefined, the hook is removed.
callback: A function to call each time QuickJS completes a "cycle" (internal VM loop),
Returns: None
dump_shapes() function
Use this for internal debugging of object shapes.
Returns: A debug string describing the internal shape hierarchy used by QuickJS.
dump_atoms() function
known by QuickJS. Helpful for diagnosing memory usage or potential key collisions.
Returns: A debug string listing all currently registered atoms (internal property keys/symbols)
dump_class() function
Shows how many objects of each class exist, useful for advanced memory or performance profiling.
Returns: A debug string describing the distribution of JS object classes in the QuickJS runtime.
dump_objects() function
useful for debugging memory leaks or object lifetimes.
Returns: A debug string listing certain internal QuickJS objects and their references,
dump_type_overheads() function
Displays memory usage breakdown for different internal object types.
Returns: A debug string describing the overheads for various JS object types in QuickJS.
stack_info() function
Internal debugging utility to examine call stack details.
Returns: An object or string describing the runtime's current stack usage and capacity.
calc_mem(value) function
Compute the approximate size of a single JS value in memory. This is a best-effort estimate.
value: A JavaScript value to analyze.
Returns: Approximate memory usage (in bytes) of that single value.
mem() function
including total allocated bytes, object counts, and more.
Retrieve an overview of the runtime’s memory usage.
Returns: An object containing a comprehensive snapshot of memory usage for the current QuickJS runtime,
mem_limit(bytes) function
Set the upper memory limit for the QuickJS runtime. Exceeding this limit may cause operations to fail or throw errors.
bytes: The maximum memory (in bytes) QuickJS is allowed to use.
Returns: None
gc_threshold(bytes) function
Set the threshold (in bytes) for QuickJS to perform an automatic GC pass when memory usage surpasses it.
bytes: The threshold (in bytes) at which the engine triggers automatic garbage collection.
Returns: None
max_stacksize(bytes) function
Set the maximum stack size for QuickJS. If exceeded, the runtime may throw a stack overflow error.
bytes: The maximum allowed stack size (in bytes) for QuickJS.
Returns: None
memstate() function
Gives a quick overview of the memory usage, including malloc size and other allocations.
Returns: A simpler memory usage object (malloc sizes, etc.) for the QuickJS runtime.
gc() function
Force an immediate, full garbage collection pass, reclaiming unreachable memory.
Returns: None
eval(src, filename) function
Execute a string of JavaScript code in the current QuickJS context.
src: A string of JavaScript source code to evaluate.
filename: (Optional) A string for the filename or label, used in debugging or stack traces.
Returns: The result of evaluating the given source code.