javascript function name vs function literal usage

Question

When testing for a partial evaluation function:

function partialEval(fn)
   {
      var sliceMethod = Array.prototype.slice; 
      if(arguments.length > 1)
      {
        var aps = sliceMethod.call(arguments, 1);
      }


      return function () {
         return fn.apply(this,aps.concat(  sliceMethod.call(arguments)  ));  
    };

    }




    var x= function add(a,b,c,d){
     console.debug(a +  " - " +  b +  " - " +  c +  " - " +  d);
     return a+b+c+d; 

    }

    var pa = partialEval(add, 1,2); // Query here
    var zz = pa(3,4);
    console.debug(zz);

What is the difference between calling partialEval(add,1,2) and partialEval (x,1,2)? I understand that x is a function literal here and using x gives the correct results. But when I use add as a function name sent to the partialEval method the output is coming as 3. Can someone explain the execution differences between the two?

thanks.

@primvdb: It might in IE. IE has bugs regarding named function expressions. — Felix Kling
– Felix Kling, Commented Aug 24, 2011 at 19:44
@primvdb: It works in firefox 3.6 and I am testing with firebug.. — Anna
– Anna, Commented Aug 24, 2011 at 20:43

javamonkey79 · Accepted Answer · 2011-09-25 23:25:56Z

3

When you do:

var x = function add(a,b,c,d){
  // code...
}

add should only exist inside the function (and refer to itself). Outside of the function you need to use x, add will be undefined.

edited Sep 25, 2011 at 23:25

javamonkey79

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answered Aug 24, 2011 at 19:47

gen_Eric

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7 Comments

Anna Over a year ago

add is not coming as undefined. Check in FF

gen_Eric Over a year ago

@Anna: Seems browsers all handle this differently. I suggest not declaring functions like this, because the behavior as you can see is not the same.

Anna Over a year ago

Can one say that function literal definitions are almost equivalent to anonymous function then? Is there no difference in terms of usage?

gen_Eric Over a year ago

@Anna: var x = function(a,b,c,d){} is exactly the same as function x(a,b,c,d){}.

gen_Eric Over a year ago

@Anna: What do you mean by "function literal definitions are almost equivalent to anonymous function"?

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Small Hadron Collider · Accepted Answer · 2011-08-24 19:50:03Z

0

I believe that named functions are hoisted whereas function literals are not.

No reason to use both types though. I generally use an anonymous function literal as in my mind it maps them as objects, which they are.

answered Aug 24, 2011 at 19:50

Small Hadron Collider

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