How to check whether an attribute is a function in Javascript

Question

In Javascript, I want to check if an attribut (or object) is a function or not.

My Present code:

if (this.execute != null)
{
    this.execute();
}

Error: Object doesn't support this property or method.

i want to do something like

if (this.execute != null and isExecutableFunction(this.execute)== true )
{
    this.execute();
}

Is there anyway in Javascript to check if an attribute (or object ) is a function or not
Any help shall be appreciated.
Thanks.

Answer 1

Try this:

if(typeof this.execute == 'function') { 
this.execute(); 
}

Answer 2

You could use typeof

var func = function(){};
alert(typeof func)

If you put this in your firebug console and run it, you get function as the return.

So you just need to check for it.

Answer 3

Try this. Works fine in jsfiddle. I changed this to t since I wasn't working inside a function. Try it with line 2 both remarked and unremarked.

var t= new Object;

//t.execute = function() { alert('executing'); };

if(t.execute)  
   t.execute();
else
    //code here when execute fails
  alert('Function could not execute');