Function.caller

Deprecated
This feature is no longer recommended. Though some browsers might still support it, it may have already been removed from the relevant web standards, may be in the process of being dropped, or may only be kept for compatibility purposes. Avoid using it, and update existing code if possible; see the compatibility table at the bottom of this page to guide your decision. Be aware that this feature may cease to work at any time.

The function.caller property returns the function that invoked the specified function. This property is restricted to non-strict functions.

Description

If the function f was invoked by the top level code, the value of f.caller is null, otherwise it's the function that called f.

This property replaces the obsolete arguments.caller property of the arguments object.

The special property __caller__, which returned the activation object of the caller thus allowing to reconstruct the stack, was removed for security reasons.

Notes

Note that in case of recursion, you can't reconstruct the call stack using this property. Consider:

function f(n) { g(n - 1); }
function g(n) { if (n > 0) { f(n); } else { stop(); } }
f(2);

At the moment stop() is called the call stack will be:

f(2) -> g(1) -> f(1) -> g(0) -> stop()

The following is true:

stop.caller === g && f.caller === g && g.caller === f

so if you tried to get the stack trace in the stop() function like this:

var f = stop;
var stack = 'Stack trace:';
while (f) {
  stack += '\n' + f.name;
  f = f.caller;
}

the loop would never stop.

Examples

Checking the value of a function's caller property

The following code checks the value a function's caller property.

function myFunc() {
  if (myFunc.caller == null) {
    return 'The function was called from the top!';
  } else {
    return 'This function\'s caller was ' + myFunc.caller;
  }
}

Specifications

Not part of any specification. Implemented in JavaScript 1.5.

Browser compatibility

Update compatibility data on GitHub
DesktopMobileServer
ChromeEdgeFirefoxInternet ExplorerOperaSafariAndroid webviewChrome for AndroidFirefox for AndroidOpera for AndroidSafari on iOSSamsung InternetNode.js
caller
Non-standard
Chrome Full support 1Edge Full support 12Firefox Full support 1IE Full support 8Opera Full support 9.6Safari Full support 3WebView Android Full support 1Chrome Android Full support 18Firefox Android Full support 4Opera Android Full support 10.1Safari iOS Full support 1Samsung Internet Android Full support 1.0nodejs Full support Yes

Legend

Full support  
Full support
Non-standard. Expect poor cross-browser support.
Non-standard. Expect poor cross-browser support.

See also