JS 动画基础

获取元素的样式

getStyle函数

1 function getStyle(element, attr) {
2     if(element.currentStyle) {
3         //针对IE
4         return element.currentStyle[attr];
5     } else {
6         //针对Firefox
7         return getComputedStyle(element, false)[attr];
8     }
9 }

View Code

此函数返回的是一个字符串，需要调用 parseInt() 或者 parseFloat() 将返回的结果转换为数字值。

简单动画

HTML

 1 <!doctype html>
 2 <html>
 3     <head>
 4         <meta charset="UTF-8">
 5         <title>简单动画</title>
 6         <link rel="stylesheet" href="css/style.css">
 7         <script type="text/javascript" src="js/script.js"></script>
 8     </head>
 9     <body>
10         <div id="box">
11             <img src="http://pic1.win4000.com/wallpaper/c/537b28b60619b.jpg" alt="A picture" style="240px;height:180px" />
12             <span>萌萌哒</span>
13         </div>
14     </body>
15 </html>

View Code

CSS

 1 * {
 2     margin: 0;
 3     padding: 0;
 4 }
 5 
 6 #box {
 7     padding: 5px;
 8     margin: 10px;
 9     border: 1px solid #aaa;
10     border-radius: 5px;
11     width: 240px;
12     box-shadow: 0 0 1px #aaa, 0 0 2px #aaa;
13     position: absolute;
14     top: 0;
15     left: -260px;
16     cursor: pointer;
17 }
18 
19 #box span {
20     position: absolute;
21     display: block;
22     width: 20px;
23     background-color: black;
24     color: white;
25     margin-left: 245px;
26     margin-top: -125px;
27 }

View Code

JavaScript

 1 window.onload = function() {
 2     move();
 3 }
 4 
 5 function move() {
 6     var box = document.getElementById("box");
 7     box.timer = null;
 8     box.onmouseover = function() {
 9         animation(box, "left", 0, 1, 10);
10     };
11     box.onmouseout = function() {
12         animation(box, "left", -260, 1, 10);
13     };
14 }
15 
16 
17 // 简单动画，接收5个参数：动画元素、动画属性、目标值、变化速度、定时器时间
18 function animation(element, attr, target, speed, timing) {
19     clearInterval(element.timer);
20     element.timer = setInterval(function() {
21         var curValue = parseInt(getStyle(element, attr));
22         var count = speed;
23         if(curValue < target) {
24             count = speed;
25         } else if(curValue > target) {
26             count = -speed;
27         } else {
28             count = 0;
29         }
30         if(curValue == target) {
31             clearInterval(element.timer);
32         } else {
33             element.style[attr] = curValue + count + "px";
34             console.log(curValue);
35         }
36     }, timing)
37 }
38 
39 function getStyle(element, attr) {
40     if(element.currentStyle) {
41         return element.currentStyle[attr];
42     } else {
43         return getComputedStyle(element, false)[attr];
44     }
45 }

View Code

动画效果看这里！

缓冲动画

HTML

 1 <!doctype html>
 2 <html>
 3     <head>
 4         <meta charset="UTF-8">
 5         <title>缓冲动画</title>
 6         <link rel="stylesheet" href="css/style.css">
 7         <script type="text/javascript" src="js/script.js"></script>
 8     </head>
 9     <body>
10         <div id="box">
11             <img src="http://pic1.win4000.com/wallpaper/c/537b28b60619b.jpg" alt="A picture" style="240px;height:180px" />
12             <span>萌萌哒</span>
13         </div>
14     </body>
15 </html>

View Code

CSS

 1 * {
 2     margin: 0;
 3     padding: 0;
 4 }
 5 
 6 #box {
 7     padding: 5px;
 8     margin: 10px;
 9     border: 1px solid #aaa;
10     border-radius: 5px;
11     width: 240px;
12     box-shadow: 0 0 1px #aaa, 0 0 2px #aaa;
13     position: absolute;
14     top: 0;
15     left: -260px;
16 }
17 
18 #box span {
19     position: absolute;
20     display: block;
21     width: 20px;
22     background-color: black;
23     color: white;
24     margin-left: 245px;
25     margin-top: -125px;
26     cursor: pointer;
27 }

View Code

JavaScript

 1 window.onload = function() {
 2     move();
 3 }
 4 
 5 function move() {
 6     var box = document.getElementById("box");
 7     box.timer = null;
 8     box.onmouseover = function() {
 9         animation(box, "left", 0, 10, 50);
10     };
11     box.onmouseout = function() {
12         animation(box, "left", -260, 10, 50);
13     };
14 }
15 
16 // 缓冲动画，接收5个参数：动画元素、动画属性、目标值、变化速度、定时器时间
17 function animation(element, attr, target, speed, timing) {
18     clearInterval(element.timer);
19     element.timer = setInterval(function() {
20         var curValue = parseInt(getStyle(element, attr));
21         var count = (target - curValue) / speed;
22         count = (count > 0) ? Math.ceil(count) : Math.floor(count);
23         if(curValue == target) {
24             clearInterval(element.timer);
25         } else {
26             element.style[attr] = curValue + count + "px";
27         }
28     }, timing)
29 }
30 
31 function getStyle(element, attr) {
32     if(element.currentStyle) {
33         return element.currentStyle[attr];
34     } else {
35         return getComputedStyle(element, false)[attr];
36     }
37 }

View Code

动画效果看这里！

透明度动画

HTML

 1 <!doctype html>
 2 <html>
 3     <head>
 4         <meta charset="UTF-8">
 5         <title>透明度动画</title>
 6         <link rel="stylesheet" href="css/style.css">
 7         <script type="text/javascript" src="js/script.js"></script>
 8     </head>
 9     <body>
10         <div id="box"></div>
11     </body>
12 </html>

View Code

CSS

1 #box {
2     width: 100px;
3     height: 100px;
4     background-color: blue;
5     border: 5px solid #333;
6     border-radius: 5px;
7     opacity: 0.5;
8 }

View Code

JavaScript

 1 window.onload = function() {
 2     var box = document.getElementById("box");
 3     box.timer = null;
 4     box.onmouseover = function() {
 5         changeOpacity(box, 100, 2, 10, 100);
 6     }
 7     box.onmouseout = function() {
 8         changeOpacity(box, 30, 2, 10, 100);
 9     }
10 }
11 
12 function changeOpacity(element, target, method, speed, timing) {
13     clearInterval(element.timer);
14     element.timer = setInterval(function() {
15         var curValue = Math.round(parseFloat(getStyle(element, "opacity")) * 100);
16         switch(method) {
17             case 1:
18                 var count = speed;
19                 if(curValue < target) {
20                     count = speed;
21                 } else if(curValue > target) {
22                     count = -speed;
23                 } else {
24                     count = 0;
25                 }
26                 break;
27             case 2:
28                 var count = (target - curValue) / speed;
29                 count = (count > 0) ? Math.ceil(count) : Math.floor(count);
30                 break;
31             default:
32                 var count = (target - curValue) / speed;
33                 count = (count > 0) ? Math.ceil(count) : Math.floor(count);
34 
35         }
36         if(curValue == target) {
37             clearInterval(element.timer);
38         } else {
39             console.log(curValue);
40             element.style.opacity = (curValue + count) / 100;
41         }
42     }, timing)
43 }
44 
45 function getStyle(element, attr) {
46     if(element.currentStyle) {
47         return element.currentStyle[attr];
48     } else {
49         return getComputedStyle(element, false)[attr];
50     }
51 }

View Code

动画效果看这里！

【1】使用 getStyle 函数获取的 opacity 属性是一个浮点数，不能使用 parseInt() 对其进行转化，应该使用 parseFloat() 。

将 opacity 的值乘以 100 ，然后调用 Math.round() ，将浮点数变成整数。（永远不要比较两个浮点数是否相等，结局绝对会出人意料。）

基础动画框架

HTML

 1 <!doctype html>
 2 <html>
 3     <head>
 4         <meta charset="UTF-8">
 5         <title>动画框架演示</title>
 6         <link rel="stylesheet" href="css/style.css">
 7         <script type="text/javascript" src="js/script.js"></script>
 8     </head>
 9     <body>
10         <div id="box"></div>
11     </body>
12 </html>

View Code

CSS

 1 #box {
 2     margin: 10px;
 3     border: 5px solid #333;
 4     border-radius: 5px;
 5     box-shadow: 0 0 1px #333, 0 0 2px #333;
 6     width: 100px;
 7     height: 100px;
 8     background-color: blue;
 9     opacity: 0.3;
10     position: absolute;
11     left: 0;
12     top: 0;
13 }

View Code

JavaScript

 1 window.onload = function() {
 2     move();
 3 }
 4 
 5 function move() {
 6     var box = document.getElementById("box");
 7     box.timer = null;
 8     box.onmouseover = function() {
 9         animation(box, {left:300}, 2, 20, 50, function() {
10             animation(box, {200, height:200, opacity:100}, 2, 20, 50)
11         })
12     }
13     box.onmouseout = function() {
14         animation(box, {left:0}, 2, 20, 50, function() {
15             animation(box, {100, height:100, opacity:50}, 2, 20, 50)
16         })
17     }
18 }
19 
20 // 动画函数接收 6 个参数：动画元素、json 数据、运动方式、变化速度、定时器时间、回调函数
21 // 其中，json 数据的格式为 {attr1: target1, attr2: target2}
22 // method 参数传入 1 则表示匀速运动，传入 2 则表示缓冲运动
23 function animation(element, json, method, speed, timing, fn) {
24     clearInterval(element.timer);
25     element.timer = setInterval(function() {
26         var flag = true;
27         for(var attr in json) {
28             var curValue = 0;
29             if(attr == "opacity") {
30                 curValue = Math.round(parseFloat(getStyle(element, attr)) * 100);
31             } else {
32                 curValue = parseInt(getStyle(element, attr));
33             }
34             switch(method) {
35                 case 1:
36                     var count = speed;
37                     if(curValue < json[attr]) {
38                         count = speed;
39                     } else if(curValue > json[attr]) {
40                         count = -speed;
41                     } else {
42                         count = 0;
43                     }
44                     break;
45                 case 2:
46                     var count = (json[attr] - curValue) / speed;
47                     count = (count > 0) ? Math.ceil(count) : Math.floor(count);
48                     break;
49                 default:
50                     var count = (json[attr] - curValue) / speed;
51                     count = (count > 0) ? Math.ceil(count) : Math.floor(count);
52             }
53 
54             if(curValue != json[attr]) {
55                 flag = false;
56             } 
57             if(attr == "opacity") {
58                 element.style.opacity = (curValue + count) / 100;
59                 console.log(curValue);
60             } else {
61                 element.style[attr] = curValue + count + "px";
62             }
63         }
64         if(flag) {
65             clearInterval(element.timer);
66             if(fn) {
67                 fn();
68             }
69         }
70     }, timing);
71 }
72 
73 function getStyle(element, attr) {
74     if(element.currentStyle) {
75         return element.currentStyle[attr];
76     } else {
77         return getComputedStyle(element, false)[attr];
78     }
79 }

View Code

动画效果看这里！

【1】如果需要将元素恢复到动画之前的样子，动画的运动方式应该一致，否则在特殊情况下会出一些 bug 。

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原文地址：https://www.cnblogs.com/cc156676/p/5779905.html