JavaScript面向对象_拖拽

来源：互联网发布：数据的存储过程编辑：程序博客网时间：2024/06/05 09:43

面向对象有个前提：

前提：所有东西都必须包含在onload里
改写：不能有函数嵌套，可以有全局变量
过程，如下
- onload改成构造函数，
- 全局变量改成属性（通过this）
- 函数改写成方法

<!DOCTYPE HTML><html><head><meta http-equiv="Content-Type" content="text/html; charset=utf-8"><title>面向对象的继承-1</title><style>#div1 {width: 100px; height: 100px; background: red; position: absolute;}</style><script>window.onload = function() {    var oDiv = document.getElementById('div1');    oDiv.onmousedown = function(ev) {        var ev = ev || event;        var disX = ev.clientX - this.offsetLeft;        var disY = ev.clientY - this.offsetTop;        document.onmousemove = function(ev) {            var ev = ev || event;            oDiv.style.left = ev.clientX - disX + 'px';            oDiv.style.top = ev.clientY - disY + 'px';        }        document.onmouseup = function() {            document.onmousemove = document.onmouseup = null;        }    }}</script></head><body>    <div id="div1"></div></body></html>

把局部变量改成全局变量

<!DOCTYPE HTML><html><head><meta http-equiv="Content-Type" content="text/html; charset=utf-8"><title>面向对象的继承-2</title><style>#div1 {width: 100px; height: 100px; background: red; position: absolute;}</style><script>var oDiv=null;var disX=0;var disY=0;window.onload = function() {    oDiv = document.getElementById('div1');    oDiv.onmousedown = fnDown;}function fnMove(ev) {    var ev = ev || event;    oDiv.style.left = ev.clientX - disX + 'px';    oDiv.style.top = ev.clientY - disY + 'px';}function fnUp() {    document.onmousemove = document.onmouseup = null;}function fnDown(ev) {    var ev = ev || event;    disX = ev.clientX - this.offsetLeft;    disY = ev.clientY - this.offsetTop;    document.onmousemove = fnMove;    document.onmouseup =fnUp;}</script></head><body>    <div id="div1"></div></body></html>

引用块内容

<!DOCTYPE HTML><html><head><meta http-equiv="Content-Type" content="text/html; charset=utf-8"><title>面向对象的继承-2</title><style>#div1 {width: 100px; height: 100px; background: red; position: absolute;}#div2 {width: 100px; height: 100px; background: red; position: absolute;top:120px;}</style><script>window.onload=function(){    new Drag('div1');    new Drag('div2');}function Drag(id) {    var _this=this;    this.disX=0;    this.disY=0;    this.oDiv = document.getElementById(id);    this.oDiv.onmousedown = function(){        _this.fnDown()    };}Drag.prototype.fnDown=function (ev) {    var ev = ev || event;    var _this=this;    this.disX = ev.clientX - this.oDiv.offsetLeft;    this.disY = ev.clientY - this.oDiv.offsetTop;    document.onmousemove = function(){        _this.fnMove();    };    document.onmouseup =function(){        _this.fnUp();    };}Drag.prototype.fnMove=function(ev) {    var ev = ev || event;    this.oDiv.style.left = ev.clientX - this.disX + 'px';    this.oDiv.style.top = ev.clientY - this.disY + 'px';}Drag.prototype.fnUp=function () {    document.onmousemove = null;    document.onmouseup = null}</script></head><body>    <div id="div1"></div>    <div id="div2"></div></body></html>

<!DOCTYPE HTML><html><head><meta http-equiv="Content-Type" content="text/html; charset=utf-8"><title>面向对象的继承-2</title><style>#div1 {width: 100px; height: 100px; background: red; position: absolute;}#div2 {width: 100px; height: 100px; background: red; position: absolute;top:120px;}</style><script>window.onload=function(){    new Drag('div1');    new Drag('div2');}function Drag(id) {    var _this=this;    this.disX=0;    this.disY=0;    this.oDiv = document.getElementById(id);    this.oDiv.onmousedown = function(){        _this.fnDown()    };}Drag.prototype.fnDown=function (ev) {    var ev = ev || event;    var _this=this;    this.disX = ev.clientX - this.oDiv.offsetLeft;    this.disY = ev.clientY - this.oDiv.offsetTop;    document.onmousemove = function(){        _this.fnMove();    };    document.onmouseup =function(){        _this.fnUp();    };}Drag.prototype.fnMove=function(ev) {    var ev = ev || event;    this.oDiv.style.left = ev.clientX - this.disX + 'px';    this.oDiv.style.top = ev.clientY - this.disY + 'px';}Drag.prototype.fnUp=function () {    document.onmousemove = null;    document.onmouseup = null}</script></head><body>    <div id="div1"></div>    <div id="div2"></div></body></html>

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