The JavaScript strict mode-only exception "deprecated caller or arguments usage" occurs when the deprecated Function.prototype.caller
or Function.prototype.arguments
properties are used.
On this page
ReferenceError: deprecated caller or arguments usage
Message
TypeError: 'caller', 'callee', and 'arguments' properties may not be accessed on strict mode functions or the arguments objects for calls to them (V8-based & Firefox)
TypeError: 'arguments', 'callee', and 'caller' cannot be accessed in this context. (Safari)
Error type
TypeError
in strict mode only.
What went wrong?
In strict mode, the Function.prototype.caller
or Function.prototype.arguments
properties are used and shouldn't be. They are deprecated, because they leak the function caller, are non-standard, hard to optimize and potentially a performance-harmful feature.
Examples
Deprecated function.caller or arguments.callee
Function.prototype.caller
and arguments.callee
are deprecated (see the reference articles for more information).
"use strict";
function myFunc() {
if (myFunc.caller === null) {
return "The function was called from the top!";
} else {
return `This function's caller was ${myFunc.caller}`;
}
}
myFunc();
// TypeError: 'caller', 'callee', and 'arguments' properties may not be accessed on strict mode functions or the arguments objects for calls to them
Function.prototype.arguments
Function.prototype.arguments
is deprecated (see the reference article for more information).
"use strict";
function f(n) {
g(n - 1);
}
function g(n) {
console.log(`before: ${g.arguments[0]}`);
if (n > 0) {
f(n);
}
console.log(`after: ${g.arguments[0]}`);
}
f(2);
console.log(`returned: ${g.arguments}`);
// TypeError: 'caller', 'callee', and 'arguments' properties may not be accessed on strict mode functions or the arguments objects for calls to them
See also
© 2005–2023 MDN contributors.
Licensed under the Creative Commons Attribution-ShareAlike License v2.5 or later.
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Errors/Deprecated_caller_or_arguments_usage