Can someone explain the significance of this code snippet [Javascript]

Question

function play()
{
if (typeof Game_Interval != "undefined")
clearInterval(Game_Interval);
Game_Interval = setInterval(paint, 60);
allowPressKeys = true;
}

What exactly is Game_Interval and why isnt it declared as a variable in the code? The above mentioned function is a part of a snake game program using javascript and HTML canvas tag.

Game_Interval is likely some kind of JavaScript object on which clearInterval and setInterval operate. Of course, there's no way to know without seeing all the code. You've shared only a small part out of context. — ThisClark
– ThisClark, Commented Apr 8, 2017 at 4:48

Vaibhav Nigam · Accepted Answer · 2017-04-08 04:49:13Z

0

setInterval calls a function (paint() in your case) at regular intervals (60ms in your case) and returns a Number, representing the ID value of the timer that is set. Use this value with the clearInterval() method to cancel the timer.

Since Game_Interval is not declared, javascript will implicitly declare it as a global variable.

answered Apr 8, 2017 at 4:49

Vaibhav Nigam

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1 Comment

Shon Aufdaded Over a year ago

Makes sense. Cheers!

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