前言：小时候，在我印象中，每到快过年的时候就有很多卖炮仗的，一般也就是阳历的12月份到明年的正月15号卖炮仗的商家比较多，省下买辣条的钱去买炮仗，在老家也就过年和除夕两天及正月15日这几天放烟花和炮仗比较猛，现在年纪大了，听不得炮仗那种噪声了，也考虑到环保，工作之后的程序员以代码的形式演绎一下烟花的效果。

javascript

完整代码及必要的配图

效果图

首先我们下看一段小视频

前端程序员自制春节元宵烟花

项目结构

一个网页+两个配图

html

引入两个背景图片衬托一下，先写几段话用于在播放烟花的字幕，可以根据自己的兴趣随意添加，直接复制粘帖修改文字即可。

<canvas id='cas' style="background-color:rgba(0,5,24,1)">浏览器不支持canvas</canvas>
      <div class="city"><img src="city.png" alt="" /></div>
      <img src="moon.png" alt="" id="moon" style="visibility: hidden;"/>
      <div style="display:none">
          <div class="shape">孙叫兽祝大家</div>
        <div class="shape">2022年</div>
        <div class="shape">新年快乐</div>
        <div class="shape">财富自由</div>
        <div class="shape">合家幸福</div>
             <div class="shape">万事如意</div>
             <div class="shape">心想事成</div>
             <div class="shape">财源广进</div>
      </div>

javascript

主要控制文字显示的位置，文字及烟花出现的频率。

var canvas = document.getElementById("cas");
        var ocas = document.createElement("canvas");
        var octx = ocas.getContext("2d");
        var ctx = canvas.getContext("2d");
          ocas.width = canvas.width = window.innerWidth;
          ocas.height = canvas.height = window.innerHeight;
        var bigbooms = [];
        window.onload = function(){
          initAnimate()
          }
        function initAnimate(){
          drawBg();
            lastTime = new Date();
          animate();
          }
        var lastTime;
        function animate(){
            ctx.save();
            ctx.fillStyle = "rgba(0,5,24,0.1)";
            ctx.fillRect(0,0,canvas.width,canvas.height);
            ctx.restore();
          var newTime = new Date();
                 if(newTime-lastTime>500+(window.innerHeight-767)/2){
            var random = Math.random()*100>2?true:false;
            var x = getRandom(canvas.width/5 , canvas.width*4/5);
            var y = getRandom(50 , 200);
            if(random){
              var bigboom = new Boom(getRandom(canvas.width/3,canvas.width*2/3) ,2,"#FFF" , {x:x , y:y});
                bigbooms.push(bigboom)
              }
            else {
              var bigboom = new Boom(getRandom(canvas.width/3,canvas.width*2/3) ,2,"#FFF" , {x:canvas.width/2 , y:200} , document.querySelectorAll(".shape")[parseInt(getRandom(0, document.querySelectorAll(".shape").length))]);
                bigbooms.push(bigboom)
              }
              lastTime = newTime;
            console.log(bigbooms)
            }
            stars.foreach(function(){
            this.paint();
            })
          drawMoon();
            bigbooms.foreach(function(index){
            var that = this;
            if(!this.dead){
              this._move();
              this._drawLight();
              }
            else{
              this.booms.foreach(function(index){
                if(!this.dead) {
                  this.moveTo(index);
                  }
                else if(index === that.booms.length-1){
                    bigbooms[bigbooms.indexOf(that)] = null;
                  }
                })
              }
            });
          raf(animate);
          }
        function drawMoon(){
          var moon = document.getElementById("moon");
          var centerX = canvas.width-200 , centerY = 100 , width = 80;
          if(moon.complete){
              ctx.drawImage(moon , centerX , centerY , width , width )
            }
          else {
              moon.onload = function(){
                ctx.drawImage(moon ,centerX , centerY , width , width)
              }
            }
          var index = 0;
          for(var i=0;i<10;i++){
              ctx.save();
              ctx.beginPath();
              ctx.arc(centerX+width/2 , centerY+width/2 , width/2+index , 0 , 2*Math.PI);
              ctx.fillStyle="rgba(240,219,120,0.005)";
              index+=2;
              ctx.fill();
              ctx.restore();
            }
          }
        Array.prototype.foreach = function(callback){
          for(var i=0;i<this.length;i++){
            if(this[i]!==null) callback.apply(this[i] , [i])
            }
          }
        var raf = window.requestAnimationFrame || window.webkitRequestAnimationFrame || window.mozRequestAnimationFrame || window.oRequestAnimationFrame || window.msRequestAnimationFrame || function (callback) { window.setTimeout(callback, 1000 / 60); };
          canvas.onclick = function(){
          var x = event.clientX;
          var y = event.clientY;
          var bigboom = new Boom(getRandom(canvas.width/3,canvas.width*2/3) ,2,"#FFF" , {x:x , y:y});
            bigbooms.push(bigboom)
          }
        // canvas.addEventLisener("touchstart" , function(event){
        // var touch = event.targetTouches[0];
        // var x = event.pageX;
        // var y = event.pageY;
        // var bigboom = new Boom(getRandom(canvas.width/3,canvas.width*2/3) ,2,"#FFF" , {x:x , y:y});
        // bigbooms.push(bigboom)
        // })
        var Boom = function(x,r,c,boomArea,shape){
          this.booms = [];
          this.x = x;
          this.y = (canvas.height+r);
          this.r = r;
          this.c = c;
          this.shape = shape || false;
          this.boomArea = boomArea;
          this.theta = 0;
          this.dead = false;
          this.ba = parseInt(getRandom(80 , 100));
          }
        Boom.prototype = {
          _paint:function(){
              ctx.save();
              ctx.beginPath();
              ctx.arc(this.x,this.y,this.r,0,2*Math.PI);
              ctx.fillStyle = this.c;
              ctx.fill();
              ctx.restore();
            },
          _move:function(){
            var dx = this.boomArea.x - this.x , dy = this.boomArea.y - this.y;
            this.x = this.x+dx*0.01;
            this.y = this.y+dy*0.01;
            if(Math.abs(dx)<=this.ba && Math.abs(dy)<=this.ba){
              if(this.shape){
                this._shapBoom();
                }
              else this._boom();
              this.dead = true;
              }
            else {
              this._paint();
              }
            },
          _drawLight:function(){
              ctx.save();
              ctx.fillStyle = "rgba(255,228,150,0.3)";
              ctx.beginPath();
              ctx.arc(this.x , this.y , this.r+3*Math.random()+1 , 0 , 2*Math.PI);
              ctx.fill();
              ctx.restore();
            },
          _boom:function(){
            var fragNum = getRandom(30 , 200);
            var style = getRandom(0,10)>=5? 1 : 2;
            var color;
            if(style===1){
                color = {
                a:parseInt(getRandom(128,255)),
                b:parseInt(getRandom(128,255)),
                c:parseInt(getRandom(128,255))
                }
              }
            var fanwei = parseInt(getRandom(300, 400));
            for(var i=0;i<fragNum;i++){
              if(style===2){
                  color = {
                  a:parseInt(getRandom(128,255)),
                  b:parseInt(getRandom(128,255)),
                  c:parseInt(getRandom(128,255))
                  }
                }
              var a = getRandom(-Math.PI, Math.PI);
              var x = getRandom(0, fanwei) * Math.cos(a) + this.x;
              var y = getRandom(0, fanwei) * Math.sin(a) + this.y;
              var radius = getRandom(0 , 2)
              var frag = new Frag(this.x , this.y , radius , color , x , y );
              this.booms.push(frag);
              }
            },
          _shapBoom:function(){
            var that = this;
            putValue(ocas , octx , this.shape , 5, function(dots){
              var dx = canvas.width/2-that.x;
              var dy = canvas.height/2-that.y;
              for(var i=0;i<dots.length;i++){
                  color = {a:dots[i].a,b:dots[i].b,c:dots[i].c}
                var x = dots[i].x;
                var y = dots[i].y;
                var radius = 1;
                var frag = new Frag(that.x , that.y , radius , color , x-dx , y-dy);
                  that.booms.push(frag);
                }
              })
            }
          }
        function putValue(canvas , context , ele , dr , callback){
            context.clearRect(0,0,canvas.width,canvas.height);
          var img = new Image();
          if(ele.innerHTML.indexOf("img")>=0){
              img.src = ele.getElementsByTagName("img")[0].src;
            imgload(img , function(){
                context.drawImage(img , canvas.width/2 - img.width/2 , canvas.height/2 - img.width/2);
                dots = getimgData(canvas , context , dr);
              callback(dots);
              })
            }
          else {
            var text = ele.innerHTML;
              context.save();
            var fontSize =200;
              context.font = fontSize+"px 宋体 bold";
              context.textAlign = "center";
              context.textBaseline = "middle";
              context.fillStyle = "rgba("+parseInt(getRandom(128,255))+","+parseInt(getRandom(128,255))+","+parseInt(getRandom(128,255))+" , 1)";
              context.fillText(text , canvas.width/2 , canvas.height/2);
              context.restore();
              dots = getimgData(canvas , context , dr);
            callback(dots);
            }
          }
        function imgload(img , callback){
          if(img.complete){
              callback.call(img);
            }
          else {
              img.onload = function(){
                callback.call(this);
              }
            }
          }
        function getimgData(canvas , context , dr){
          var imgData = context.getImageData(0,0,canvas.width , canvas.height);
            context.clearRect(0,0,canvas.width , canvas.height);
          var dots = [];
          for(var x=0;x<imgData.width;x+=dr){
            for(var y=0;y<imgData.height;y+=dr){
              var i = (y*imgData.width + x)*4;
              if(imgData.data[i+3] > 128){
                var dot = {x:x , y:y , a:imgData.data[i] , b:imgData.data[i+1] , c:imgData.data[i+2]};
                  dots.push(dot);
                }
              }
            }
          return dots;
          }
        function getRandom(a , b){
          return Math.random()*(b-a)+a;
          }
        var maxRadius = 1 , stars=[];
        function drawBg(){
          for(var i=0;i<100;i++){
            var r = Math.random()*maxRadius;
            var x = Math.random()*canvas.width;
            var y = Math.random()*2*canvas.height - canvas.height;
            var star = new Star(x , y , r);
              stars.push(star);
              star.paint()
            }
          }
        var Star = function(x,y,r){
          this.x = x;this.y=y;this.r=r;
          }
        Star.prototype = {
          paint:function(){
              ctx.save();
              ctx.beginPath();
              ctx.arc(this.x , this.y , this.r , 0 , 2*Math.PI);
              ctx.fillStyle = "rgba(255,255,255,"+this.r+")";
              ctx.fill();
              ctx.restore();
            }
          }
        var focallength = 250;
        var Frag = function(centerX , centerY , radius , color ,tx , ty){
          this.tx = tx;
          this.ty = ty;
          this.x = centerX;
          this.y = centerY;
          this.dead = false;
          this.centerX = centerX;
          this.centerY = centerY;
          this.radius = radius;
          this.color = color;
          }
        Frag.prototype = {
          paint:function(){
              ctx.save();
              ctx.beginPath();
              ctx.arc(this.x , this.y , this.radius , 0 , 2*Math.PI);
              ctx.fillStyle = "rgba("+this.color.a+","+this.color.b+","+this.color.c+",1)";
              ctx.fill()
              ctx.restore();
            },
          moveTo:function(index){
            this.ty = this.ty+0.3;
            var dx = this.tx - this.x , dy = this.ty - this.y;
            this.x = Math.abs(dx)<0.1 ? this.tx : (this.x+dx*0.1);
            this.y = Math.abs(dy)<0.1 ? this.ty : (this.y+dy*0.1);
            if(dx===0 && Math.abs(dy)<=80){
              this.dead = true;
              }
            this.paint();
            }
          }

完整代码及必要的配图

点我下载

好啦，本期内容就分享到这里，我们下期见！

2023将至，前端程序员们应该一起放个烟花庆祝一下，走起

效果图

项目结构

html

javascript

完整代码及必要的配图

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