Using a javascript constructor to re-initialize an existing object

Question

I'm using this function to create a particle for my particle system:

function particle()
{
    this.speed = {x: -1.5+Math.random()*3, y: -12+Math.random()*12};
    this.location = {x: 50, y: 150};
    this.radius = 5+Math.random()*8;
    this.life = 4+Math.random()*8;
    this.remaining_life = this.life;
    this.r = 255;
    this.g = 140;
    this.b = 30;
}

and I'm using this function to update the particles characteristics during the course of my animation:

particle.prototype.updateparticle = function()
{
    this.remaining_life--;
    this.radius--;
    this.location.x += this.speed.x;
    this.location.y += this.speed.y;

    if(this.remaining_life < 0 || this.radius < 0)
    {
        this.speed = {x: -1.5+Math.random()*3, y: -12+Math.random()*12};
        this.location = {x: 50, y: 150};
        this.radius = 5+Math.random()*8;
        this.life = 4+Math.random()*8;
        this.remaining_life = this.life;
        this.r = 255;
        this.g = 140;
        this.b = 30;    
    }
}

Is there a way with which I can avoid the redundant code?

Also I tried using this = new particle() and it didn't work. I can't think of a reason why it shouldn't work. why doesn't it?

And on a totally unrelated note, is Firefox incapable of handling particle animations? Chrome uses 5% of my CPU. Firefox uses around 30 and still lags! I have an i5 2500k so that shouldn't be a problem. I'm running the latest versions of both.

Answer 1

Apply the function, passing the current object as the this argument:

particle.prototype.updateparticle = function()
{
    this.remaining_life--;
    this.radius--;
    this.location.x += this.speed.x;
    this.location.y += this.speed.y;

    if(this.remaining_life < 0 || this.radius < 0)
    {
        particle.apply(this);
    }
}

Answer 2

Create a prototype function to initialize the values

function particle() {
    this.init();
}

particle.prototype.init = function(){
    this.speed = {x: -1.5+Math.random()*3, y: -12+Math.random()*12};
    this.location = {x: 50, y: 150};
    this.radius = 5+Math.random()*8;
    this.life = 4+Math.random()*8;
    this.remaining_life = this.life;
    this.r = 255;
    this.g = 140;
    this.b = 30;
}

particle.prototype.updateparticle = function() {
    this.remaining_life--;
    this.radius--;
    this.location.x += this.speed.x;
    this.location.y += this.speed.y;

    if(this.remaining_life < 0 || this.radius < 0) {
        this.init();  
    }
}

Answer 3

You can make it another function and invoke whenever required.

function particle()
{
    this.initialize();
}

particle.prototype.initialize = function(){
    this.speed = {x: -1.5+Math.random()*3, y: -12+Math.random()*12};
    this.location = {x: 50, y: 150};
    this.radius = 5+Math.random()*8;
    this.life = 4+Math.random()*8;
    this.remaining_life = this.life;
    this.r = 255;
    this.g = 140;
    this.b = 30;    
}

particle.prototype.updateparticle = function()
{
    this.remaining_life--;
    this.radius--;
    this.location.x += this.speed.x;
    this.location.y += this.speed.y;

    if(this.remaining_life < 0 || this.radius < 0)
    {
        this.initialize();
    }
}

Answer 4

function particle(x, y, r, g, b) {
  this.location = {x: x, y: y};
  this.r = r;
  this.g = g;
  this.b = b;

  // Group everything that randomises in update()
  this.update = function() {
    this.speed = {x: -1.5+Math.random()*3, y: -12+Math.random()*12};
    this.radius = 5+Math.random()*8;
    this.life = 4+Math.random()*8;
    this.remaining_life = this.life;
  }

  this.update();
}


particle.prototype.updateparticle = function() {
  this.remaining_life--;
  this.radius--;
  this.location.x += this.speed.x;
  this.location.y += this.speed.y;

  if(this.remaining_life < 0 || this.radius < 0) {
    this.update();
  }
}

//Instantiation
var p1 = new particle(50, 150, 255, 140, 30);