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.

• pimvdb: add should not work here. Does it actually work?
• Felix Kling: @primvdb: It might in IE. IE has bugs regarding named function expressions.
• Anna: @primvdb: It works in firefox 3.6 and I am testing with firebug..

Answer 1

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.

• Anna: add is not coming as undefined. Check in FF
• gen_Eric: @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: Can one say that function literal definitions are almost equivalent to anonymous function then? Is there no difference in terms of usage?
• gen_Eric: @Anna: var x = function(a,b,c,d){} is exactly the same as function x(a,b,c,d){}.
• gen_Eric: @Anna: What do you mean by "function literal definitions are almost equivalent to anonymous function"?

Answer 2

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.