Search code examples
javascriptiife

Javascript Syntax: Immediately Invoked Function Expression (IIFE) with parameters

I have always seen code like this:

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

How does this code work? Which function receives which parameters?

(function(factory){
   //code here
}(function($){
  //other code here
}));
Solution 
  • function($){
  //other code here
}

    This block is passed as a parameter to the outer IIFE. It might be clearer to write it like this:

    var factoryDef = function($) { ... };

(function(factory) {
    // this is the outer IIFE
    var someVar = {};
    // you can call:
    factory(someVar);
    // the previous line calls factoryDef with param someVar
}(factoryDef));

    So factory(someVar) is the same as factoryDef({}); the latter is simply the value of factory (which is the function factoryDef) called with the value of someVar (which is {}.)

    Does that make sense?