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JS CompileScript

Compiles a script for execution.


JSObject * JS_CompileScript(JSContext *cx, JSObject *obj,
    const char *bytes, size_t length, const char *filename,
    uintN lineno);

JSObject * JS_CompileUCScript(JSContext *cx, JSObject *obj,
    const jschar *chars, size_t length, const char *filename,
    uintN lineno);
Name Type Description
cx JSContext * Pointer to a JS context from which to derive runtime information. Requires request. In a JS_THREADSAFE build, the caller must be in a request on this JSContext.
obj JSObject * The global object, or NULL. If the JSOPTION_COMPILE_N_GO option is set in cx, the resulting script must be executed in this scope, and at most once.
source const char * or const jschar * String containing the script to compile.
length size_t The length, in characters, of source.
filename const char * Name of file or URL containing the function. Used to report filename or URL in error messages.
lineno uintN Line number of the first line of source. Must be greater than zero. Used to report the offending line in the file or URL if an error occurs.


JS_CompileScript compiles a script, source, for execution. JS_CompileUCScript is the Unicode version of the function.

The script is associated with a JS object. source is the string containing the text of the script. length indicates the size of the text version of the script in characters.

filename is the name of the file (or URL) containing the script. This information is included in error messages if an error occurs during compilation. Similarly, lineno is used to report the line number of the script or file where an error occurred during compilation. If the script is not part of a larger document, lineno should be 1 (as the first line of a file is universally considered to be line 1, not line 0).

On success, JS_CompileScript and JS_CompileUCScript return an object representing the newly compiled script. Otherwise, they report an error and return NULL.

To compile a script from an external file source rather than passing the actual script as an argument, use


instead of



See Also

The JSAPI User Guide contains example code using compiled scripts.

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JS_DecompileScript, JS_EvaluateScript, JS_ExecuteScript

Document Tags and Contributors

Last updated by: Jorend,