console.log javascript [Function]

Question

I'm trying to log a function in javascript:

console.log(callback)
>>[Function]

I want to see what the function is. Can I do that? Thanks.

score 188 · Accepted Answer · edited Jan 04 '14 at 18:11

188

If it's a user defined function you can use:

console.log(callback.toString());

Otherwise you'll just get something like [native code] since built in functions are not written in JavaScript.

Example:

function x(){}

// Prints "function x(){}"
(function(callback){ console.log(callback.toString()); })(x);

edited Jan 04 '14 at 18:11

BenMorel

answered Feb 27 '12 at 06:26

Paul

Wouldn't `if(window.console){ console.log(' write in console ') }` - be a precaution ? – Istiaque Ahmed Mar 19 '13 at 08:07
16

No because the question is tagged with node.js which indicates that there will not be a window at all and console.log can always be expected. http://nodejs.org/api/stdio.html – foiseworth Apr 23 '14 at 19:42
3

@foiseworth link dead – Suraj Jain Jan 07 '18 at 06:41

1 Answers1