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

Try the following code:

function getStackTrace(){
  var f = arguments.callee;
  var ret = [];
  var item = {};
  var iter = 0;

  while ( f = f.caller ){
      // Initialize
    item = {
      name: f.name || null,
      args: [], // Empty array = no arguments passed
      callback: f
    };

      // Function arguments
    if ( f.arguments ){
      for ( iter = 0; iter<f.arguments.length; iter++ ){
        item.args[iter] = f.arguments[iter];
      }
    } else {
      item.args = null; // null = argument listing not supported
    }

    ret.push( item );
  }
  return ret;
}

Worked for me in Firefox-21 and Chromium-25.

Answer 2

here is a function to get full stacktrace:

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

Answer 3

Another way around this problem is to simply pass the name of the calling function as a parameter.

For example:

function reformatString(string, callerName) {

    if (callerName === "uid") {
        string = string.toUpperCase();
    }

    return string;
}

Now, you could call the function like this:

function uid(){
    var myString = "apples";

    reformatString(myString, function.name);
}

My example uses a hard coded check of the function name, but you could easily use a switch statement or some other logic to do what you want there.

Answer 4

I wanted to add my fiddle here for this:

http://jsfiddle.net/bladnman/EhUm3/

I tested this is chrome, safari and IE (10 and 8). Works fine. There is only 1 function that matters, so if you get scared by the big fiddle, read below.

Note: There is a fair amount of my own "boilerplate" in this fiddle. You can remove all of that and use split's if you like. It's just an ultra-safe" set of functions I've come to rely on.

There is also a "JSFiddle" template in there that I use for many fiddles to simply quick fiddling.

Answer 5

I think the following code piece may be helpful:

window.fnPureLog = function(sStatement, anyVariable) {
    if (arguments.length < 1) { 
        throw new Error('Arguments sStatement and anyVariable are expected'); 
    }
    if (typeof sStatement !== 'string') { 
        throw new Error('The type of sStatement is not match, please use string');
    }
    var oCallStackTrack = new Error();
    console.log(oCallStackTrack.stack.replace('Error', 'Call Stack:'), '\n' + sStatement + ':', anyVariable);
}

Execute the code:

window.fnPureLog = function(sStatement, anyVariable) {
    if (arguments.length < 1) { 
        throw new Error('Arguments sStatement and anyVariable are expected'); 
    }
    if (typeof sStatement !== 'string') { 
        throw new Error('The type of sStatement is not match, please use string');
    }
    var oCallStackTrack = new Error();
    console.log(oCallStackTrack.stack.replace('Error', 'Call Stack:'), '\n' + sStatement + ':', anyVariable);
}

function fnBsnCallStack1() {
    fnPureLog('Stock Count', 100)
}

function fnBsnCallStack2() {
    fnBsnCallStack1()
}

fnBsnCallStack2();

The log looks like this:

Call Stack:
    at window.fnPureLog (<anonymous>:8:27)
    at fnBsnCallStack1 (<anonymous>:13:5)
    at fnBsnCallStack2 (<anonymous>:17:5)
    at <anonymous>:20:1 
Stock Count: 100

Answer 6

Just want to let you know that on PhoneGap/Android the name doesnt seem to be working. But arguments.callee.caller.toString() will do the trick.