Different function declarations

Question

I was told that you can declare functions in JavaScript more than 1 way. ex.

// One way
function sqrt(x){
   return x * x;
}

// Second way
var sqrtAlt = function (x){
   return x * x;
}

What is the difference between these two function declarations?
The output is same but must have a reason to have two ways?
I am also curious about how you would use them.
Lastly, are there any other ways?

Thanks.

I think the second way should be `var sqrtAlt = function(x){ ... }` — Fabien Quatravaux, Mar 17 '13 at 15:21

score 0 · Answer 1 · edited May 23 '17 at 11:58

0

When you are defining

function sqrt(x){
   return x * x;
}

is that the function name appears in Firebug debugger.

Functions that are declared as

var sqrtAlt = function (x){
 return x * x;
 }

come up as anonymous.

Also check out this Thread

edited May 23 '17 at 11:58

Community

1
1

answered Mar 17 '13 at 15:24

Rahul Tripathi

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score 0 · Answer 2 · answered Mar 17 '13 at 15:25

0

They are basically the same thing, but in the second example you additionally assign the function to a variable. This way of creating a function is very useful when overriding an existing function of some object, let's say:

window.alert = function(text)
{
    // Do something ...
};

answered Mar 17 '13 at 15:25

mirrormx

3,969
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There is a very important difference: In the first example the function is available at the beginning of the execution context, in the second not until the assignment statement has been executed. – a better oliver Mar 17 '13 at 15:54

Different function declarations

2 Answers2