How to Determine the Details of the Caller Function in JavaScript?

Discovering Caller Function Details in JavaScript

Determining the origin of a function call can provide valuable insights for debugging and analysis. This article explores how to obtain the line number and source URL of the caller function in JavaScript.

Getting the Caller's Line Number

The provided code effectively retrieves the name of the caller function using the arguments.callee.caller object. However, obtaining the line number requires a different approach. One method involves utilizing the Error object:

<code class="js">function getErrorObject() {
  try {
    throw Error('');
  } catch (err) {
    return err;
  }
}

var err = getErrorObject();
var caller_line = err.stack.split("\n")[4];
var index = caller_line.indexOf("at ");
var clean = caller_line.slice(index + 2, caller_line.length);</code>

The stack property of the Error object contains a stack trace that includes the line numbers and source URLs of the function calls that led to the error. By parsing this string, you can extract the line number of the caller function.

Retrieving the Caller's Source URL

Similarly, the source URL can be acquired from the stack property of the Error object:

<code class="js">var caller_url = err.stack.split("\n")[4];
var index = caller_url.indexOf("(");
var clean = caller_url.slice(index + 1, caller_url.length - 1);</code>

The portion of the stack trace between the parentheses contains the source URL of the caller function.

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