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HTML

              
                <canvas id="game"></canvas>
              
            
!

CSS

              
                * { margin: 0; padding: 0;}

body, html {width:100%; height:100%;}

canvas {display:block;}

              
            
!

JS

              
                var canvas;
var stage;
var width = 650;
var height = 400;
var particles = [];
var max = 60;
var mouseX=0;
var mouseY=0;

var speed=3;
var size=20;

//The class we will use to store particles. It includes x and y
//coordinates, horizontal and vertical speed, and how long it's
//been "alive" for.
function Particle(x, y, xs, ys) {
  this.x=x;
  this.y=y;
  this.xs=xs;
  this.ys=ys;
  this.life=0;
}

function resizeCanvas() {
  setTimeout(function() {
    width = window.innerWidth;
    height = window.innerHeight;
    canvas.width = width;
    canvas.height = height;
    canvas.style.width = width + "px";
    canvas.style.height = height + "px";
    mouseX=canvas.width/2;
    mouseY=canvas.height*0.8;
   stage.globalCompositeOperation="lighter"
  }, 0);
}

function init() {
  
  //Reference to the HTML element
  canvas=document.getElementById("game");
  
  resizeCanvas();
  
  //See if the browser supports canvas
  if (canvas.getContext) {
    
    //Get the canvas context to draw onto
    stage = canvas.getContext("2d");
    
    //Makes the colors add onto each other, producing
    //that nice white in the middle of the fire
    stage.globalCompositeOperation="xor";
    
    //Update the mouse position
    canvas.addEventListener("mousemove", getMousePos);
    
    window.addEventListener("resize", function() {
      resizeCanvas();
      stage.globalCompositeOperation="lighter";
      mouseX=canvas.width/2;
      mouseY=canvas.height*0.8;
    });
    
    //Update the particles every frame
    var timer=setInterval(update,40);
    
  } else {
    alert("Canvas not supported.");
  }
}

function getMousePos (evt) {
  var rect = canvas.getBoundingClientRect();
  var root = document.documentElement;
  
  // return mouse position relative to the canvas
  mouseX = evt.clientX - rect.left - root.scrollLeft;
  mouseY = evt.clientY - rect.top - root.scrollTop;
}

function update() {

  //Adds ten new particles every frame
  for (var i=0; i<10; i++) {
    
    //Adds a particle at the mouse position, with random horizontal and vertical speeds
    var p = new Particle(mouseX, mouseY, (Math.random()*2*speed-speed)/2, 0-Math.random()*2*speed);
    particles.push(p);
  }
  
  //Clear the stage so we can draw the new frame
  stage.clearRect(0, 0, width, height);
  
  //Cycle through all the particles to draw them
  for (i=0; i<particles.length; i++) {
    
    //Set the file colour to an RGBA value where it starts off red-orange, but progressively gets more grey and transparent the longer the particle has been alive for
    stage.fillStyle = "rgba("+(260-(particles[i].life*2))+","+((particles[i].life*2)+50)+","+(particles[i].life*2)+","+(((max-particles[i].life)/max)*0.4)+")";
    
    stage.beginPath();
    //Draw the particle as a circle, which gets slightly smaller the longer it's been alive for
    stage.arc(particles[i].x,particles[i].y,(max-particles[i].life)/max*(size/2)+(size/2),0,2*Math.PI);
    stage.fill();
    
    //Move the particle based on its horizontal and vertical speeds
    particles[i].x+=particles[i].xs;
    particles[i].y+=particles[i].ys;
    
    particles[i].life++;
    //If the particle has lived longer than we are allowing, remove it from the array.
    if (particles[i].life >= max) {
      particles.splice(i, 1);
      i--;
    }
  }
}

init();
              
            
!
999px

Console