What means construction (function () { ... } ) () [duplicate]

Question

What means this construction in JavaScript :

   (function (){
      alert("bla");
   })();

?

Answer 1

The acronym for this pattern is an "IIFE" or an Immediately Invoked Function Expression.

It basically creates an anonymous function function(){}

function(){alert("bla");}

then wraps it as an expression ()

(function(){alert("bla");})

then executes it ()

(function(){alert("bla");})()

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Note that at this point, you can pass arguments in as well like this:

(function(text){alert(text);})("bla")