CODEWITHSUNDEEP
javascriptfunctionobject
Navaneeth
Navaneeth

Reputation: 2584

declaring and defining functions in javascript



I have a doubt regarding functions(objects) in javascript.

I have 2 pieces of code like,

    var a= function(){
    console.log('abc')
     }


and

     var a= (function(){
     console.log('abc')
     })


what is the difference between these two>>
thanx:)

Upvotes: 3

Views: 134

Answers (5)

Willem Mulder
Willem Mulder

Reputation: 13994

There is a difference.

( and ) constitute a grouping. A grouping can only contain an expression, thus any function inside it will be an expression and not a declaration.

Since ECMA specifies that a function declaration must always have a function name, and a function expression may omit it, you will be able to do the following

(function() {});

while the following declaration is not valid

function() {};

It won't matter that often, but still... Read this in-depth article for more: http://kangax.github.com/nfe/

Upvotes: 1

Scott
Scott

Reputation: 2793

As has been said, the two examples you've given are essentially the same.

This question has a lot more information contained in the answers regarding parentheses usage, might be worth your time to spin through!

Why are parenthesis used to wrap a javascript function call?

Upvotes: 0

James Allardice
James Allardice

Reputation: 165951

There is no practical difference. They will both result in an anonymous function being assigned to a.

The first is a "simple assignment". In the second, the parentheses are acting as a "grouping operator", which does one thing:

The production PrimaryExpression : ( Expression ) is evaluated as follows:

  • Return the result of evaluating Expression. This may be of type Reference.

So the grouping operator will return the function contained within it, and assign it to a, just like the first example.

Upvotes: 1

Guffa
Guffa

Reputation: 700212

There is no difference. You have a function expression, and you can put any number of parentheses around an expression.

Just as this:

a = 42;

is the same as this:

a = (42);

and this:

a = (((((42)))));

Upvotes: 1

Roman
Roman

Reputation: 504

There is no difference now, but if you add another parenthesis () after second function it will run function without invocation.

 var a= (function(){
     console.log('abc')
     })()

it will print 'abc' straightaway

Upvotes: 1

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