CODEWITHSUNDEEP
javascript
troy0412
troy0412

Reputation: 31

Parentheses and semicolon after function definition

Recently I saw a function in someone else's code which looked like below:

function xyz(){ //function code here ;
} ();

I dont understand the (); after the function definition.

Can someone tell me what is the significance of (); and when should one use it in JavaScript ?

Upvotes: 3

Views: 260

Answers (1)

Denys Séguret
Denys Séguret

Reputation: 382092

The code you show doesn't compile.

With parenthesis added, this would be a named immediately invoked function :

(function xyz(){ //function code here ;
}) ();

Most often those functions are anonymous :

(function(){
   var a; // a isn't visible outside
   // code using a
})();

The code is directly called, as without a function definition, but the point of such a function is to define a scope (which can only be the global scope or a function) so that the scope's variable don't leak in the enclosing one. This pattern is very useful for making your code clean : You don't add any variable in the outer scope and you can't erase an existing one.

Here the function also has a name, which can be used inside for recursion.

(function xyz(){
   var a; // a isn't visible outside
   // code using a and calling xyz
})();

Upvotes: 3

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