CODEWITHSUNDEEP
javascriptsettimeout
rib3ye
rib3ye

Reputation: 2923

Confused about first argument in setTimeout

I'm having great trouble understanding the first argument for setTimeout and how the delay argument effects it.

The way I understand setTimeout is: 

setTimeout(foo, don't even think about foo until x miliseconds has passed)

But if we consider this code:

<div id="mine"></div>
<script type="text/javascript">

function go(){
        var myDiv = document.getElementById("mine");
        myDiv.innerHTML = "Hello World";    
}

setTimeout(go(), 2000)
</script>

go is run right away without waiting 2 seconds.

As many before me have pointed out, setTimeout(go(), 2000) is asking for the return value when I actually want setTimeout(go, 2000).

Frankly, I don't understand the difference other than "one works, and one doesn't." Why doesn't the former also respect the delay argument?

Upvotes: 0

Views: 116

Answers (2)

del
del

Reputation: 140

var go = function () {
  console.log('GO GO GO!');
};

setTimeout(go, 2000);

Upvotes: -3

elclanrs
elclanrs

Reputation: 94101

A function in JavaScript is an object. go is the function object, go() executes the go function and returns its value. setTimeout expects a function, thus go, not go().

function go(){
  return 'hello';
}

console.log(go); //=> function go(){}, a function object
console.log(go()); //=> 'hello', a string returned by the function `go`

Upvotes: 7

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