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Editorial Team
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Asked: 2026-06-17T13:53:16+00:00

I want to create a periodic process with inner cycles, using javascript. Each cycle

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I want to create a periodic process with inner cycles, using javascript. Each cycle is represented by consequently changing circles – with specified time interval between them and specified time interval between cycles. The problem is also getting harder, because I also need a variable time interval between cycles and circle (which I’m going to do using random number function).

Currently I have the following code, which doesn’t work properly:

<html>
<body>

<canvas id="canv" widht="800" height="500"></canvas>
<script>

var ctx=document.getElementById("canv").getContext('2d');
var cnt=0;

var int0=self.setInterval(function(){startDraw()},5000);

function startDraw ()
{
    var int1=self.setInterval(function(){DrawC()},1000);
    cnt++;
    if (cnt==3)
    {
        int0=window.clearInterval(int0);
    }
}

function DrawC()
{
    ctx.beginPath();
    ctx.arc(200, 200, 50, 0, 2*Math.PI, true);
    ctx.fillStyle="yellow";
    ctx.fill();
    ctx.closePath();  
    var int2=self.setInterval(function(){DrawGC()},1000);
    int1=window.clearInterval(int1);
}

function DrawGC() 
{
    ctx.beginPath();
    ctx.arc(200, 200, 50, 0, 2*Math.PI, true);
    ctx.fillStyle="green";
    ctx.fill();
    ctx.closePath();  
    var int3=self.setInterval(function(){DrawWC()},1000);
    int2=window.clearInterval(int2);
}

function DrawWC() 
{
    ctx.beginPath();
    ctx.arc(200, 200, 52, 0, 2*Math.PI, true);
    ctx.fillStyle="white";
    ctx.fill();
    ctx.closePath();  
    int3=window.clearInterval(int3);
}

  function getRandomInt(min, max)
{
  return Math.floor(Math.random() * (max - min + 1)) + min;
}

</script>
</form>

</body>
</html>
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1 Answer

  1. Editorial Team

    You should make the timer variables as global. Try:

    var int0, int1, int2, int3;

    Remove these variable declarations from the functions.

    Try out this code, is this what you need?

    <html>
<body>

<canvas id="canv" widht="800" height="500"></canvas>
<script>

var ctx=document.getElementById("canv").getContext('2d');
var cnt=0;

var int0, int1, int2, int3;

circleTime = 1000;
cycleTime = 5000;


int0 = self.setInterval(startDraw, cycleTime);

function startDraw ()
{
    console.log("startDraw...");
    // Start drawing circles
    self.setTimeout(DrawC, circleTime);

    cnt++;
    if (cnt == 4)
    {
        // Stop startDraw
        int0 = window.clearInterval(int0);

        /*
        // Let's draw again
        cnt = 0;
        cycleTime = getRandomInt(5000, 10000);
        circleTime = getRandomInt(1000, 2000);
        int0 = self.setInterval(startDraw, cycleTime);
        */
    }
}

function DrawC()
{
    console.log("Circle...");

    ctx.beginPath();
    ctx.arc(200, 200, 50, 0, 2*Math.PI, true);
    ctx.fillStyle="yellow";
    ctx.fill();
    ctx.closePath();  

    self.setTimeout(DrawGC, circleTime);
}

function DrawGC() 
{
    console.log("greenCircle...");

    ctx.beginPath();
    ctx.arc(200, 200, 50, 0, 2*Math.PI, true);
    ctx.fillStyle="green";
    ctx.fill();
    ctx.closePath();  

    self.setTimeout(DrawWC, circleTime);
}

function DrawWC() 
{
    console.log("whiteCircle...");

    ctx.beginPath();
    ctx.arc(200, 200, 52, 0, 2*Math.PI, true);
    ctx.fillStyle="white";
    ctx.fill();
    ctx.closePath();  
}

function getRandomInt(min, max)
{
    return Math.floor(Math.random() * (max - min + 1)) + min;
}

</script>
</form>

</body>
</html>
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