CODEWITHSUNDEEP
javascript
Mr. PM
Mr. PM

Reputation: 19

what's the difference between putting all codes inside the "window.onload" and putting only the function name inside the "window.onload"?

what's the difference between putting all codes inside the window.onload=function(){}; and putting only the function name inside the window.onload=function(){};?

putting all codes inside the window.onload:

window.onload=function() {
   function(){
       // do something here
   }
};

putting only the function name inside the window.onload:

function foo() {
   //do something here
}

window.onload=function() {
   foo();
};

what's the difference? or is there any difference between them?

Upvotes: 0

Views: 84

Answers (4)

Shravan Chaurasiya
Shravan Chaurasiya

Reputation: 109

First thing , You can't declare function inside function . As you first did ,  
You can write some query inside function.  But if you want use your query again 
and again then you have to declare a function and you will put your query. 
Then you will call that function from other function inside the same page.

Upvotes: 0

Davide
Davide

Reputation: 475

It is very similar!

In the first case you declared a function only when window.onload is fired.

In the second case you declared a "globally" function accessible from window.onload event

See this plunker demo: demo

Upvotes: 1

Ramanlfc
Ramanlfc

Reputation: 8354

In the first case all your code in centralized in a anonymous function ,which is good since you aren't polluting the global namescpace.

In the second case , foo will be available globally in your js ,which could cause a clash if you or someone using your js file redefines foo

Upvotes: 0

Marcos Pérez Gude
Marcos Pérez Gude

Reputation: 22158

If you declare it inside the window.onload, you only be able to use it when window.onload fires, not before. If you need to use the function before than hole document is loaded, you can't. Otherwise, if you write the function outside, you only call it when the event fires, but you can use it as soon as be defined.

Upvotes: 2

Related Questions