Finding the line number FROM WHERE the call to current function occured

Question

I have a lightweight logging function. To keep it simple its something like:

function log(msg){
    console && console.log && console.log(msg);
}
which i have in a seperated file "Logging.js".

Now from another file lets say "hello.js" i do:

log("Hello");

Now if i make calls to that function the console will always display Logging.js:2 as the place where the logging occured. So there is no chance to determine from where the message originated. The log message should say hello.js:1.

Is it possible to find out from where the log function is called, find out the line number of the call and then manipulate the line number displayed by the console?

Or is there an easier solution?

Caution, please read carefully: Its NOT about the current line number. It's about the line number from where the function call occured and its about how to manipulate the log output so that it displays the line number FROM WHERE the function has been called. It's not about Errors or catching Errors.

I already postet this question some time ago and it was downvoted and declared as a duplicate of How can I determine the current line number in JavaScript? in no time, but it its not. This question is not about finding the current line number.

You can get lots of information from the Stack trace that some browsers can produce. Just throw an exception, and catch it, and check it's stack trace. — Poetro, Dec 06 '13 at 15:46
also see http://stackoverflow.com/questions/6787711/javascript-backtrace — JimiDini, Dec 06 '13 at 15:47

score 3 · Answer 1 · answered Dec 06 '13 at 15:50

You can construct an Error object and look at the "stack" property:

$(function() {
  function a() {
    b();
  }

  function b() {
    c();
  }

  function c() {
    $('#e').html(new Error().stack.replace(/\n/g, '<br>'));
  }

  a();
});

JSBin

That'll show:

c@http://jsbin.com/aLuKUSU/1:33
b@http://jsbin.com/aLuKUSU/1:29
a@http://jsbin.com/aLuKUSU/1:25
@http://jsbin.com/aLuKUSU/1:36
b.Callbacks/c@http://ajax.googleapis.com/ajax/libs/jquery/1/jquery.min.js:3
b.Callbacks/p.fireWith@http://ajax.googleapis.com/ajax/libs/jquery/1/jquery.min.js:3
.ready@http://ajax.googleapis.com/ajax/libs/jquery/1/jquery.min.js:3
H@http://ajax.googleapis.com/ajax/libs/jquery/1/jquery.min.js:3

The "stack" property of Error objects is not standardized, but it's available in Firefox, Chrome, IE10+, and Safari 6. (Don't know about mobile browsers.)

Finding the line number FROM WHERE the call to current function occured

1 Answers1