Thursday, October 24, 2019

closures - What is the purpose of a self executing function in javascript?

Answer


Answer




In javascript, when would you want to use this:



(function(){
    //Bunch of code...
})();



over this:



//Bunch of code...

Answer



Its all about variable scoping. Variables declared in the self executing function are, by default, only available to code within the self executing function. This allows code to be written without concern of how variables are named in other blocks of javascript code.



For example:




(function(){ 
    var foo = 3; 
    alert(foo); 
})(); 

alert(foo);


This will first alert "3" and then throw an error on the next alert because foo is not defined.


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