What does ? mean in Javascript.

Gerb68 · 06-03-2014 09:31PM #1

Can anyone tell me what the question mark indicates in the Javascript code below?

      for(var i = 0; i < 10; i++){
	
        var s = parseInt(scores[i]);
	var val = (!isNaN(s) ? s : 0 );

      }

I have search everywhere but can not find any reference to ? in Javascript.
It is from a HTML5 game which can be sourced here:
http://www.developerdrive.com/2013/09/html5-javascript-gem-game-with-saved-scoreboard/

Thanx for any help.

Ballyv24 · 06-03-2014 09:39PM

In Java the following is the case (so presume JavaScript is the same)

if (a > b) {
max = a;
}
else {
max = b;
}

is the same logic as:

max = (a > b) ? a : b;

so in English.. if the statement in brackets is true.. then max is given the value of the a variable , otherwise max is given the value of the b variable

Source: http://www.cafeaulait.org/course/week2/43.html

dumb_parade · 06-03-2014 09:40PM

It's similar to if/else
Syntax is (test some Boolean operation ? Return this value if true : return this value if false)
In this case it checks if s is a number(isNaN(s)) or not. If it's not it sets val to 0.

Banta · 06-03-2014 09:42PM

Answered above as I was posting... in more detail I might add.

Gerb68 · 06-03-2014 09:48PM

Perfect. Thanx a lot guys. Appreciate it.

smcelhinney · 08-03-2014 09:25AM

Its called the ternary operator.

http://en.wikipedia.org/wiki/Ternary_operation

What does ? mean in Javascript.

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