实现物体移动 - Githubissues

goldEli commented 4 years ago

用js实现物体往复运动，具体效果如下：

Untitled

完善以下代码

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>物体移动</title>
  <style>
    body{
      position: relative;
    }
    .box{
      width: 100px;
      height: 100px;
      background-color: red;
      position: absolute;
      top: 0;
      left: 0;
    }
  </style>
</head>
<body>
  <div id="js-box" class="box"></div>
  <script>
    // 用js实现，box 的往复运动
  </script>
</body>
</html>

lurasso commented 4 years ago

<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>物体移动</title>
  <style>
    body{
      position: relative;
    }
    .box{
      width: 100px;
      height: 100px;
      background-color: red;
      position: absolute;
      top: 0;
      left: 1;
    }
  </style>
</head>
<body>
  <div id="js-box" class="box"></div>
  <script>

        //方法1 通过设置box中的初始值
        var div = document.getElementById('js-box');
        var length = 1;
        if(isNaN(parseInt(div.style.left))){
            div.style.left="0px";
            }   
        var timer = setInterval(function(){                 
            div.style.left = parseInt(div.style.left) + length + 'px';
            if(parseInt(div.style.left) > 500 || parseInt(div.style.left) <=0){
                length *= -1;
            }
            }, 1);
        //方法2 通过获取box中的内部样式
        var div = document.getElementById("js-box");
        all_style = window.getComputedStyle(div,null);
        var length = 1;
        var timer1 = setInterval(function(){                 
            div.style.left = parseInt(all_style.left) + length + 'px';
            if(parseInt(div.style.left) > 500 || parseInt(div.style.left) <=0){
                length *= -1;
            }
            }, 1);

  </script>
</body>

748580573 commented 4 years ago

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>物体移动</title>
  <style>
    body{
      position: relative;
    }
    .box{
      width: 100px;
      height: 100px;
      background-color: red;
      position: absolute;
      top: 0;
      left: 0;
    }
  </style>
</head>
<body>
  <div id="js-box" class="box"></div>
  <script>

    var direction = 1;
    var box = document.getElementById("js-box");

    var timer = setInterval(function() {
      var currentPosition = box.offsetLeft;
      if(direction > 0){
      var nextPosition = currentPosition + 2;
      box.style.left = nextPosition + "px";
      }else {
      var nextPosition = currentPosition - 2;
      box.style.left = nextPosition + "px";
      }

      if(box.offsetLeft > 1200){
        direction = 0;
      }else if(box.offsetLeft < 10){
        direction = 1;
      }
    },8);
  </script>
</body>
</html>

FireDragonZL commented 4 years ago

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>物体移动</title>
  <style>
    body{
      position: relative;
    }
    .box{
      width: 100px;
      height: 100px;
      background-color: red;
      position: absolute;
      top: 0px;
      left: 0px;
    }
  </style>
</head>
<body>
  <div id="js-box" class="box"></div>
  <script>

    var box_move = window.setInterval(move,200);
    var count = 0;
    var step = -50;
    function move(){
        var js_box = document.getElementById("js-box");

        if(count%6 == 0){
            step = -step;
        }

        current_left = js_box.offsetLeft + step;
        js_box.style.left = current_left + "px";
        count++;
    }
  </script>
</body>
</html>

goldEli commented 4 years ago

一般每秒30针就可以骗过人眼，人眼就可以把一张张滚动的图看成动画

goldEli / Front-End-Training

实现物体移动 #24