CODEWITHSUNDEEP
javascript
Nathan
Nathan

Reputation: 2387

If the result of an anonymous function is assigned to a variable, is that function called every time the variable is called?

So if have:

var num = (function(){
  return 1 + 1;
})();

Will that function be processed every time I use that variable? Or is it only processed the first time the browser reads over the script and the return result 'permanently' assigned to that variable?

Upvotes: 1

Views: 27

Answers (3)

Lyes BEN
Lyes BEN

Reputation: 1010

Let's make a test, consider the following script :

var timestamp = (function(){
 return Date.now();
})();

console.log('variable at time t : ' + timestamp);

setTimeout(function() {
  console.log('variable at time t+1s : ' + timestamp);
}, 1000);

This returns the same timestamp, we can conclude that the timestamp variable is assigned the value of the self-calling function only once.

Upvotes: 1

Ozan
Ozan

Reputation: 3739

(function(){ return 1 + 1; })();

is a self-executing anonymous function. Which means it will be executed as it is defined once and its value returned. If you want the function to be assigned to a variable simply use

var func = function(){ }

Upvotes: 0

Pointy
Pointy

Reputation: 413846

JavaScript is not a lazy language. ("Imperative" is one way to describe the language; I'm not the one to give the most accurate term.) The expression on the right-hand side of the = assignment operator will be evaluated once, and the result will be stored in the variable.

Upvotes: 2

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