How do you find out the caller function in JavaScr

Question

function main()
{
   Hello();
}

function Hello()
{
  // How do you find out the caller function is 'main'?
}

Is there a way to find out the call stack at all?

Answer 1

As far as I know, we have 2 way for this from given sources like this-

1. arguments.caller

   function whoCalled()
   {
       if (arguments.caller == null)
          console.log('I was called from the global scope.');
       else
          console.log(arguments.caller + ' called me!');
   }
   

2. Function.caller

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

Think u have your answer :).

Answer 2

If you just want the function name and not the code, and want a browser-independent solution, use the following:

var callerFunction = arguments.callee.caller.toString().match(/function ([^\(]+)/)[1];

Note that the above will return an error if there is no caller function as there is no [1] element in the array. To work around, use the below:

var callerFunction = (arguments.callee.caller.toString().match(/function ([^\(]+)/) === null) ? 'Document Object Model': arguments.callee.caller.toString().match(/function ([^\(]+)/)[1], arguments.callee.toString().match(/function ([^\(]+)/)[1]);

Answer 3

I know you mentioned "in Javascript", but if the purpose is debugging, I think it's easier to just use your browser's developer tools. This is how it looks in Chrome: Just drop the debugger where you want to investigate the stack.

Answer 4

As none of previous answers works like what I was looking for(getting just the last function caller not a function as a string or callstack) I post my solution here for those who are like me and hope this will work for theme:

function getCallerName(func)
{
  if (!func) return "anonymous";
  let caller = func.caller;
  if (!caller) return "anonymous";
  caller = caller.toString();
  if (!caller.trim().startsWith("function")) return "anonymous";
  return caller.substring(0, caller.indexOf("(")).replace("function","");
}


//  Example of how to use "getCallerName" function

function Hello(){
console.log("ex1  =>  " + getCallerName(Hello));
}

function Main(){
Hello();

// another example
console.log("ex3  =>  " + getCallerName(Main));
}

Main();

Answer 5

To recap (and make it clearer) ...

this code:

function Hello() {
    alert("caller is " + arguments.callee.caller.toString());
}

is equivalent to this:

function Hello() {
    alert("caller is " + Hello.caller.toString());
}

Clearly the first bit is more portable, since you can change the name of the function, say from "Hello" to "Ciao", and still get the whole thing to work.

In the latter, in case you decide to refactor the name of the invoked function (Hello), you would have to change all its occurrences :(

Answer 6

Try accessing this:

arguments.callee.caller.name