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JS EvaluateScript

Compile and execute a script.


JSBool JS_EvaluateScript(JSContext *cx, JSObject *obj,
    const char *src, uintN length, const char *filename,
    uintN lineno, jsval *rval);

JSBool JS_EvaluateUCScript(JSContext *cx, JSObject *obj,
    const jschar *src, uintN length, const char *filename,
    uintN lineno, jsval *rval);
Name Type Description
cx JSContext * The context in which to run the script. Requires request. In a JS_THREADSAFE build, the caller must be in a request on this JSContext.
obj JSObject * The scope in which to execute the script. This parameter is documented in detail at JS_ExecuteScript.
src const char * or const jschar * String containing the script to compile and execute.
length uintN The length of src, in characters.
filename const char * Name of file or URL containing the script. Used to report filename or URL in error messages.
lineno uintN Line number. Used to report the offending line in the file or URL if an error occurs.
rval jsval * Out parameter. On success, if rval is not NULL, *rval receives the result value.


JS_EvaluateScript compiles and executes a script in the specified scope, obj. JS_EvaluateUCScript is the Unicode version of the function.

src 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 used in 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.

rval is an optional out parameter. If it is non-null, then on success, the result value is stored in *rval. This value is determined the same way as for the standard eval function. In the common case where the script is just an expression, the result value is simply the value of that expression. More generally, the result value is the value of the last-executed expression statement in the script that isn't in a function.

If a script compiles and executes successfully, JS_EvaluateScript or JS_EvaluateUCScript stores the result in *rval, if non-null, and returns JS_TRUE. Otherwise it returns JS_FALSE and the value left in *rval is undefined.

See Also

MXR ID Search for JS_EvaluateScript
MXR ID Search for JS_EvaluateUCScript

JS_CompileFile, JS_CompileScript, JS_DecompileScript, JS_DestroyScript, JS_EvaluateScriptForPrincipals

Document Tags and Contributors

 Last updated by: Jorend,