How to create the flame effect with HTML5 Canvas and JavaScript

Instructions on how to create the flame effect with HTML5 Canvas and JavaScript
HTML
As usual, we're still just a canvas element to create the effect.
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<!-- Lets make a cool flame effect -->
<canvas id="canvas"></canvas>
CSS
You only need to apply the following simple format:
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* {margin: 0; padding: 0;}
#canvas {display: block;}
Javascript
And here is the entire script will help you create the flame effect:
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<script language="JavaScript">
window.onload = function(){
    var canvas = document.getElementById("canvas");
    var ctx = canvas.getContext("2d");
      
    //Make the canvas occupy the full page
    var W = window.innerWidth, H = window.innerHeight;
    canvas.width = W;
    canvas.height = H;
      
    var particles = [];
    var mouse = {};
      
    //Lets create some particles now
    var particle_count = 100;
    for(var i = 0; i < particle_count; i++)
    {
        particles.push(new particle());
    }
      
    //finally some mouse tracking
    canvas.addEventListener('mousemove', track_mouse, false);
      
    function track_mouse(e)
    {
        //since the canvas = full page the position of the mouse
        //relative to the document will suffice
        mouse.x = e.pageX;
        mouse.y = e.pageY;
    }
      
    function particle()
    {
        //speed, life, location, life, colors
        //speed.x range = -2.5 to 2.5
        //speed.y range = -15 to -5 to make it move upwards
        //lets change the Y speed to make it look like a flame
        this.speed = {x: -2.5+Math.random()*5, y: -15+Math.random()*10};
        //location = mouse coordinates
        //Now the flame follows the mouse coordinates
        if(mouse.x && mouse.y)
        {
            this.location = {x: mouse.x, y: mouse.y};
        }
        else
        {
            this.location = {x: W/2, y: H/2};
        }
        //radius range = 10-30
        this.radius = 10+Math.random()*20;
        //life range = 20-30
        this.life = 20+Math.random()*10;
        this.remaining_life = this.life;
        //colors
        this.r = Math.round(Math.random()*255);
        this.g = Math.round(Math.random()*255);
        this.b = Math.round(Math.random()*255);
    }
      
    function draw()
    {
        //Painting the canvas black
        //Time for lighting magic
        //particles are painted with "lighter"
        //In the next frame the background is painted normally without blending to the
        //previous frame
        ctx.globalCompositeOperation = "source-over";
        ctx.fillStyle = "black";
        ctx.fillRect(0, 0, W, H);
        ctx.globalCompositeOperation = "lighter";
          
        for(var i = 0; i < particles.length; i++)
        {
            var p = particles[i];
            ctx.beginPath();
            //changing opacity according to the life.
            //opacity goes to 0 at the end of life of a particle
            p.opacity = Math.round(p.remaining_life/p.life*100)/100
            //a gradient instead of white fill
            var gradient = ctx.createRadialGradient(p.location.x, p.location.y, 0, p.location.x, p.location.y, p.radius);
            gradient.addColorStop(0, "rgba("+p.r+", "+p.g+", "+p.b+", "+p.opacity+")");
            gradient.addColorStop(0.5, "rgba("+p.r+", "+p.g+", "+p.b+", "+p.opacity+")");
            gradient.addColorStop(1, "rgba("+p.r+", "+p.g+", "+p.b+", 0)");
            ctx.fillStyle = gradient;
            ctx.arc(p.location.x, p.location.y, p.radius, Math.PI*2, false);
            ctx.fill();
              
            //lets move the particles
            p.remaining_life--;
            p.radius--;
            p.location.x += p.speed.x;
            p.location.y += p.speed.y;
              
            //regenerate particles
            if(p.remaining_life < 0 || p.radius < 0)
            {
                //a brand new particle replacing the dead one
                particles[i] = new particle();
            }
        }
    }
      
    setInterval(draw, 33);
}
</script>
I hope through this article, you will understand and be able to add creative effects from html5 canvas element. 
I wish you success!

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