鼠标拖动改变DIV等网页元素的大小的最佳实践

1.初次实现

1.1 html代码

<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en"><head><meta http-equiv="Content-Type" content="text/html; charset=utf-8" /><title>div change width by drag</title><script src="../jQuery/jquery-1.8.3.min.js" type="text/javascript"></script></head><body><h1>div change width by drag</h1><div id="pos" style="color:red"></div><div id="myDiv" style="border:2px solid red;width:300px;height:50px;margin-left: 100px;margin-top: 20px"></div></body>
</html>

1.2 js代码

　　　　　　　　　 var eleLeft = $('#myDiv').offset().left;var isMouseDown = false;var borderLen = 4; //左右边框
                $('#myDiv').bind({mousedown:function(e){var ele = $(this);var rightPos = eleLeft   ele.width()   borderLen;if(rightPos-5 <= e.pageX && e.pageX <= rightPos){isMouseDown = true;}},mousemove:function(e){var ele =  $(this);var rightPos = eleLeft   ele.width()   borderLen;$('#pos').text("x:" e.pageX   " eleLeft:" eleLeft " rightPos:" rightPos);if(rightPos-5 <= e.pageX && e.pageX <= rightPos){ele.css('cursor','e-resize');}else{if(!isMouseDown){ele.css('cursor','auto');}}if(isMouseDown){ele.width((e.pageX-eleLeft-borderLen) 'px');  //新鼠标位置-div距左-borderLen
                        }},mouseup:function(e){isMouseDown = false;}});

1.3 结果

只能往左拖动使div宽度变小，往右拖动没有用！原因往右拖动鼠标mousemove事件无法被div捕获了。拖动时也很难停下来！所以得改进。

2.再次改进

　　　　　　　　　　$('#myDiv').bind({mousedown:function(e){var ele = $(this);var rightPos = eleLeft   ele.width()   borderLen;if(rightPos-5 <= e.pageX && e.pageX <= rightPos){isMouseDown = true;}}});$('body').bind({mousemove:function(e){var ele = $('#myDiv');var rightPos = eleLeft   ele.width()   borderLen;$('#pos').text("x:" e.pageX   " eleLeft:" eleLeft " rightPos:" rightPos);if(rightPos-5 <= e.pageX && e.pageX <= rightPos){ele.css('cursor','e-resize');}else{if(!isMouseDown){ele.css('cursor','auto');}}if(isMouseDown){ele.width((e.pageX-eleLeft-borderLen) 'px');  
                        }},mouseup:function(e){isMouseDown = false;}});

这次解决了上述问题，可以往右拖，并且随时可以停下来了。到这里就完成了吗？NO!

当我引入一个其他div，并且阻止mouseup事件冒泡情况怎么样呢？答案是，拖动到这个其它div上放开鼠标后无法停止下来！

<div id="otherDiv" style="border: 2px solid blue;width: 200px;height: 200px;margin-left: 400px"></div>

　　　　　　　　　$('#otherDiv').mouseup(function(e){//e.preventDefault(); //阻止默认行为e.stopPropagation(); //阻止事件冒泡(导致body捕获不到mouseup事件)});

3.完美解决

拖动停止可能受到其它元素的干扰，怎么解决？想到一些弹出层点击其它其它地方隐藏的功能，让我想到了，加一个遮罩层，让mouseup事件总是可以响应，不就搞定了嘛！

　　　　　　　　$('#myDiv').bind({mousedown:function(e){var ele = $(this);var rightPos = eleLeft   ele.width()   borderLen;if(rightPos-5 <= e.pageX && e.pageX <= rightPos){isMouseDown = true;//创建遮罩层，防止mouseup事件被其它元素阻止冒泡，导致mouseup事件无法被body捕获，导致拖动不能停止var bodyWidth = $('body').width();var bodyHeight = $('body').height();$('body').append('<div id="mask" style="opacity:0.2;top:0px;left:0px;background-color:green;position:absolute;z-index:9999;width:' bodyWidth 'px;height:' bodyHeight 'px;"></div>');}}});$('body').bind({mousemove:function(e){var ele = $('#myDiv');var rightPos = eleLeft   ele.width()   borderLen;$('#pos').text("x:" e.pageX   " eleLeft:" eleLeft " rightPos:" rightPos);if(rightPos-5 <= e.pageX && e.pageX <= rightPos){ele.css('cursor','e-resize');}else{if(!isMouseDown){ele.css('cursor','auto');}}if(isMouseDown){ele.width((e.pageX-eleLeft-borderLen) 'px'); 
                        }},mouseup:function(e){isMouseDown = false;$('#mask').remove();}});$('#otherDiv').mouseup(function(e){//e.preventDefault(); //阻止默认行为e.stopPropagation(); //阻止事件冒泡(导致body捕获不到mouseup事件)});

4.完整代码和最终效果

<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en"><head><meta http-equiv="Content-Type" content="text/html; charset=utf-8" /><title>div change width by drag</title><script src="../jQuery/jquery-1.8.3.min.js" type="text/javascript"></script></head><body><h1>div change width by drag</h1><div id="pos" style="color:red"></div><div id="myDiv" style="border:2px solid red;width:300px;height:50px;margin-left: 100px;margin-top: 20px"></div><div id="otherDiv" style="border: 2px solid blue;width: 200px;height: 200px;margin-left: 400px"></div></body><script type="text/javascript">$(document).ready(function(){var eleLeft = $('#myDiv').offset().left;var isMouseDown = false;var borderLen = 4; //左右边框
$('#myDiv').bind({mousedown:function(e){var ele = $(this);var rightPos = eleLeft   ele.width()   borderLen;if(rightPos-5 <= e.pageX && e.pageX <= rightPos){isMouseDown = true;//创建遮罩层，防止mouseup事件被其它元素阻止冒泡，导致mouseup事件无法被body捕获，导致拖动不能停止var bodyWidth = $('body').width();var bodyHeight = $('body').height();$('body').append('<div id="mask" style="opacity:0.2;top:0px;left:0px;background-color:green;position:absolute;z-index:9999;width:' bodyWidth 'px;height:' bodyHeight 'px;"></div>');}}});$('body').bind({mousemove:function(e){var ele = $('#myDiv');var rightPos = eleLeft   ele.width()   borderLen;$('#pos').text("x:" e.pageX   " eleLeft:" eleLeft " rightPos:" rightPos);if(rightPos-5 <= e.pageX && e.pageX <= rightPos){ele.css('cursor','e-resize');}else{if(!isMouseDown){ele.css('cursor','auto');}}if(isMouseDown){ele.width((e.pageX-eleLeft-borderLen) 'px'); 
                        }},mouseup:function(e){isMouseDown = false;$('#mask').remove();}});$('#otherDiv').mouseup(function(e){//e.preventDefault(); //阻止默认行为
                    e.stopPropagation(); //阻止事件冒泡(导致body捕获不到mouseup事件)
                });});</script>
</html>