CODEWITHSUNDEEP
javascript
UllerUller
UllerUller

Reputation: 61

simple while issue (javascript)

Can any body shed some light on why I am not able to stop and start this loop?

 <input type="button" value="start" onclick="start()">
 <input type="reset" value="stop" onClick="stop()">

var startLottery = false;

while(startLottery){
setInterval(function(){automateLottery()},120);
startLottery;
};

var start = function(){
startLottery = true;    
};

var stop = function(){
startLottery = false;   
};

Thank you

Upvotes: 1

Views: 67

Answers (4)

john_science
john_science

Reputation: 6571

Problem 1

A while loop will only execute when the operand evaluates to true.

However, you start off with your startLottery variable equal to false.

So the while loop will never execute.

Problem 2

At no point are you actually changing the value of the startLottery variable, so even if the loop did execute, it would never terminate.

Upvotes: 2

Ryan V
Ryan V

Reputation: 516

If what you provided for code is exactly as I see it, the while loop will never be entered. The page will be rendered (the inputs) and then the variable startLottery will be set to false. Next, the loop will evaluate the expression (which will always return false) and never actually enter the loop.

Upvotes: 0

jbabey
jbabey

Reputation: 46657

You cannot start and stop a loop like that. You need to use setInterval and clearInterval:

JS: 

var lotteryInterval;

var start = function(){
    lotteryInterval = setInterval(lotteryFunc, 120);
};

var stop = function(){
    clearInterval(lotteryInterval);
};

var lotteryFunc = function () {
    automateLottery();
};

HTML: 

<input type="button" value="start" onclick="start()">
<input type="reset" value="stop" onClick="stop()">

Edit: Working demo.

Upvotes: 2

bfavaretto
bfavaretto

Reputation: 71939

I believe you're looking for this (assuming you do have an automateLottery function):

var timer;

var start = function(){
    timer = setInterval(automateLottery, 120);
};

var stop = function(){
    clearInterval(timer);
};

start();

Upvotes: 0

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