How to check if a variable is a function ?

Check if the variable is a Function

This is an interesting and a pretty simple question. I did figure out few ways in which you can include this into your library. There are various ways to identify if the variable is a function. We will look for two different ways of achieving this out.

• Easiest and Best way
• function foo(v) {if (v instanceof Function) {/* do something */} };
• Next best way to do this
• function foo(v) {if (typeof v === “function”) {/* do something */} };
• The way I prefer
• function isFunction(functionToCheck) { var getType = {}; return functionToCheck && getType.toString.call(functionToCheck) === ‘[object Function]’; }

Now these are the various flows using which one can easily determine

Originally published at The Web Juice.