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今天小编来和大家分享个有关于：“前端开发怎么实现粒子进度条？”这个问题，下面是对于实现这个效果的内容分享，希望对大家有所帮助！
这个进度条插件非常有特点，它在进度展示的时候呈现粒子的动画效果，也就是说，进度条在滑动的同时，会产生一些小粒子掉落下来，效果非常酷。另外还有一个特点是随着进度的变化，进度条的颜色也会变化。
JavaScript代码：
/*========================================================*/
/* Light Loader
/*========================================================*/
var lightLoader = function(c, cw, ch){
var _this = this;
this.c = c;
this.ctx = c.getContext('2d');
this.cw = cw;
this.ch = ch;
this.loaded = 0;
this.loaderSpeed = .6;
this.loaderHeight = 10;
this.loaderWidth = 310;
this.loader = {
x: (this.cw/2) - (this.loaderWidth/2),
y: (this.ch/2) - (this.loaderHeight/2)
};
this.particles = [];
this.particleLift = 180;
this.hueStart = 0
this.hueEnd = 120;
this.hue = 0;
this.gravity = .15;
this.particleRate = 4;
/*========================================================*/
/* Initialize
/*========================================================*/
this.init = function(){
this.loop();
};
/*========================================================*/
/* Utility Functions
/*========================================================*/
this.rand = function(rMi, rMa){return ~~((Math.random()*(rMa-rMi+1))+rMi);};
this.hitTest = function(x1, y1, w1, h1, x2, y2, w2, h2){return !(x1 + w1 < x2 || x2 + w2 < x1 || y1 + h1 < y2 || y2 + h2 < y1);};
/*========================================================*/
/* Update Loader
/*========================================================*/
this.updateLoader = function(){
if(this.loaded < 100){
this.loaded += this.loaderSpeed;
} else {
this.loaded = 0;
}
};
/*========================================================*/
/* Render Loader
/*========================================================*/
this.renderLoader = function(){
this.ctx.fillStyle = '#000';
this.ctx.fillRect(this.loader.x, this.loader.y, this.loaderWidth, this.loaderHeight);
this.hue = this.hueStart + (this.loaded/100)*(this.hueEnd - this.hueStart);
var newWidth = (this.loaded/100)*this.loaderWidth;
this.ctx.fillStyle = 'hsla('+this.hue+', 100%, 40%, 1)';
this.ctx.fillRect(this.loader.x, this.loader.y, newWidth, this.loaderHeight);
this.ctx.fillStyle = '#222';
this.ctx.fillRect(this.loader.x, this.loader.y, newWidth, this.loaderHeight/2);
};
/*========================================================*/
/* Particles
/*========================================================*/
this.Particle = function(){
this.x = _this.loader.x + ((_this.loaded/100)*_this.loaderWidth) - _this.rand(0, 1);
this.y = _this.ch/2 + _this.rand(0,_this.loaderHeight)-_this.loaderHeight/2;
this.vx = (_this.rand(0,4)-2)/100;
this.vy = (_this.rand(0,_this.particleLift)-_this.particleLift*2)/100;
this.width = _this.rand(1,4)/2;
this.height = _this.rand(1,4)/2;
this.hue = _this.hue;
};
this.Particle.prototype.update = function(i){
this.vx += (_this.rand(0,6)-3)/100;
this.vy += _this.gravity;
this.x += this.vx;
this.y += this.vy;
if(this.y > _this.ch){
_this.particles.splice(i, 1);
}
};
this.Particle.prototype.render = function(){
_this.ctx.fillStyle = 'hsla('+this.hue+', 100%, '+_this.rand(50,70)+'%, '+_this.rand(20,100)/100+')';
_this.ctx.fillRect(this.x, this.y, this.width, this.height);
};
this.createParticles = function(){
var i = this.particleRate;
while(i--){
this.particles.push(new this.Particle());
};
};
this.updateParticles = function(){
var i = this.particles.length;
while(i--){
var p = this.particles[i];
p.update(i);
};
};
this.renderParticles = function(){
var i = this.particles.length;
while(i--){
var p = this.particles[i];
p.render();
};
};
/*========================================================*/
/* Clear Canvas
/*========================================================*/
this.clearCanvas = function(){
this.ctx.globalCompositeOperation = 'source-over';
this.ctx.clearRect(0,0,this.cw,this.ch);
this.ctx.globalCompositeOperation = 'lighter';
};
/*========================================================*/
/* Animation Loop
/*========================================================*/
this.loop = function(){
var loopIt = function(){
requestAnimationFrame(loopIt, _this.c);
_this.clearCanvas();
_this.createParticles();
_this.updateLoader();
_this.updateParticles();
_this.renderLoader();
_this.renderParticles();
};
loopIt();
};
};
/*========================================================*/
/* Check Canvas Support
/*========================================================*/
var isCanvasSupported = function(){
var elem = document.createElement('canvas');
return !!(elem.getContext && elem.getContext('2d'));
};
/*========================================================*/
/* Setup requestAnimationFrame
/*========================================================*/
var setupRAF = function(){
var lastTime = 0;
var vendors = ['ms', 'moz', 'webkit', 'o'];
for(var x = 0; x < vendors.length && !window.requestAnimationFrame; ++x){
window.requestAnimationFrame = window[vendors[x]+'RequestAnimationFrame'];
window.cancelAnimationFrame = window[vendors[x]+'CancelAnimationFrame'] || window[vendors[x]+'CancelRequestAnimationFrame'];
};
if(!window.requestAnimationFrame){
window.requestAnimationFrame = function(callback, element){
var currTime = new Date().getTime();
var timeToCall = Math.max(0, 16 - (currTime - lastTime));
var id = window.setTimeout(function() { callback(currTime + timeToCall); }, timeToCall);
lastTime = currTime + timeToCall;
return id;
};
};
if (!window.cancelAnimationFrame){
window.cancelAnimationFrame = function(id){
clearTimeout(id);
};
};
};
/*========================================================*/
/* Define Canvas and Initialize
/*========================================================*/
if(isCanvasSupported){
var c = document.createElement('canvas');
c.width = 400;
c.height = 100;
var cw = c.width;
var ch = c.height;
document.body.appendChild(c);
var cl = new lightLoader(c, cw, ch);
setupRAF();
cl.init();
}那么通过上文我们知道在要实现：“前端开发怎么实现粒子进度条？”这个问题我们只需要在项目中加入粒子 js 插件就可以实现这个效果了，那么以上就是本文的全部内容，希望对大家的学习有所帮助，喜欢html5的小伙伴也可以在W3Cschool中进行学习。
