JS makes parabolic motion trajectory

This time I will bring you JS to make a parabolic motion trajectory. What are the precautions for making a parabolic motion trajectory with JS. The following is a practical case, let's take a look.

The specific code is as follows:

nbsp;html >


  <meta>
  <title>抛物线运动</title>
  <style>
    .pwx_rect{position:absolute;left:10px;top:300px;background-color:#888;height:50px;width:50px;}
    .pwx_hr{border-top:2px solid #ddd;position:absolute;width:98%;left:0px;top:350px;}
  </style>
  <script>
    test = function(){
      var rect = document.getElementById("rect");
      pwx(rect,60,5); //参数2：抛物线角度，参数3：横向速度每次增加5
    }
    function pwx(rect,radian,step){
      var animate = function(opt){
        var cos = Math.cos(opt.radian*Math.PI/180);//邻边比斜边,60度的话等于1/2
        var sin = Math.sin(opt.radian*Math.PI/180);//对边比斜边,30度的话等于1/2
        var left = opt.rect.offsetLeft;
        var top = opt.rect.offsetTop;
        if(opt.radian>0){
          left+=opt.step;
          opt.radian-=1; //角度递减1
          var a = left - opt.initLeft;
          var c = (a/cos);
          var b = (sin*c);
          opt.rect.style.left = opt.initLeft+a+"px";
          opt.rect.style.top = opt.initTop-b+"px";
          setTimeout(function(){
            animate(opt);
          },10);
        }else{
          opt.rect.style.left = left+opt.step+"px";
          opt.rect.style.top = opt.initTop+"px";
        }
      }
      animate({
        step : step,
        rect : rect,
        radian : radian,
        initTop : rect.offsetTop,
        initLeft : rect.offsetLeft
      });
    }
  </script>


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<input>
  <p></p>
  <p></p>

I believe you have mastered the method after reading the case in this article. For more exciting information, please pay attention to other related articles on the PHP Chinese website!

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