2，阅读文档更进一步结合业务需求找到实现方法，了解插件中包含的属性和方法，当然在寻找是否具有某些属性和方法之前，可以先思考业务流程中可能需要的属性和方法
3，在JS宿主环境中合理使用控制台打印出实例对象，对象结构中一般都会包含目前版本支持的属性和方法，然后再结合文档介绍，获得使用方法
4，将获取到的解决方案整合到项目业务中，实现业务需求，包括数据的记录，提交服务器保存等
5，根据文档介绍验证在不同浏览器中的支持情况，做简单的测试，验证数据是否正确，合理，并在必要时调整代码
6，必要的时候将插件学习到应用的经验做一定的总结，让自己更加深入的了解
本文实例讲述了JS基于面向对象实现的拖拽库。分享给大家供大家参考。具体如下：这是一个面向对象的JS拖拽库，可设置水平锁定、垂直锁定、锁定位置、锁定范围等，设定这些范围后，只能在设定的模式下拖动，我觉得这是个挺不错的拖拽实例。
运行效果截图如下：
在线演示地址如下：
http://demo.jb51.net/js/2015/js-mxdx-draw-plug-codes/
具体代码如下：
<!DOCTYPE
html
PUBLIC
"-//W3C//DTD
XHTML
1.0
Transitional//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html
xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta
http-equiv="Content-Type"
content="text/html
charset=utf-8"
/>
<title>拖拽库</title>
<style
type="text/css">
div,h2,p{margin:0padding:0}
body{font:14px/1.5
arial}
#box{width:100pxheight:100pxbackground:#fef4ebpadding:5pxmargin:50pxborder:1px
solid
#f60}
#box
.title{height:25pxbackground:#f60}
#tool{margin-bottom:10px}
</style>
<script
type="text/javascript">
function
Drag()
{
//初始化
this.initialize.apply(this,
arguments)
}
Drag.prototype
=
{
//初始化
initialize
:
function
(drag,
options)
{
this.drag
=
this.$(drag)
this._x
=
this._y
=
0
this._moveDrag
=
this.bind(this,
this.moveDrag)
this._stopDrag
=
this.bind(this,
this.stopDrag)
this.setOptions(options)
this.handle
=
this.$(this.options.handle)
this.maxContainer
=
this.$(this.options.maxContainer)
this.maxTop
=
Math.max(this.maxContainer.clientHeight,
this.maxContainer.scrollHeight)
-
this.drag.offsetHeight
this.maxLeft
=
Math.max(this.maxContainer.clientWidth,
this.maxContainer.scrollWidth)
-
this.drag.offsetWidth
this.limit
=
this.options.limit
this.lockX
=
this.options.lockX
this.lockY
=
this.options.lockY
this.lock
=
this.options.lock
this.onStart
=
this.options.onStart
this.onMove
=
this.options.onMove
this.onStop
=
this.options.onStop
this.handle.style.cursor
=
"move"
this.changeLayout()
this.addHandler(this.handle,
"mousedown",
this.bind(this,
this.startDrag))
},
changeLayout
:
function
()
{
this.drag.style.top
=
this.drag.offsetTop
+
"px"
this.drag.style.left
=
this.drag.offsetLeft
+
"px"
this.drag.style.position
=
"absolute"
this.drag.style.margin
=
"0"
},
startDrag
:
function
(event)
{
var
event
=
event
||
window.event
this._x
=
event.clientX
-
this.drag.offsetLeft
this._y
=
event.clientY
-
this.drag.offsetTop
this.addHandler(document,
"mousemove",
this._moveDrag)
this.addHandler(document,
"mouseup",
this._stopDrag)
event.preventDefault
&&
event.preventDefault()
this.handle.setCapture
&&
this.handle.setCapture()
this.onStart()
},
moveDrag
:
function
(event)
{
var
event
=
event
||
window.event
var
iTop
=
event.clientY
-
this._y
var
iLeft
=
event.clientX
-
this._x
if
(this.lock)
return
this.limit
&&
(iTop
<
0
&&
(iTop
=
0),
iLeft
<
0
&&
(iLeft
=
0),
iTop
>
this.maxTop
&&
(iTop
=
this.maxTop),
iLeft
>
this.maxLeft
&&
(iLeft
=
this.maxLeft))
this.lockY
||
(this.drag.style.top
=
iTop
+
"px")
this.lockX
||
(this.drag.style.left
=
iLeft
+
"px")
event.preventDefault
&&
event.preventDefault()
this.onMove()
},
stopDrag
:
function
()
{
this.removeHandler(document,
"mousemove",
this._moveDrag)
this.removeHandler(document,
"mouseup",
this._stopDrag)
this.handle.releaseCapture
&&
this.handle.releaseCapture()
this.onStop()
},
//参数设置
setOptions
:
function
(options)
{
this.options
=
{
handle:
this.drag,
//事件对象
limit:
true,
//锁定范围
lock:
false,
//锁定位置
lockX:
false,
//锁定水平位置
lockY:
false,
//锁定垂直位置
maxContainer:
document.documentElement
||
document.body,
//指定限制容器
onStart:
function
()
{},
//开始时回调函数
onMove:
function
()
{},
//拖拽时回调函数
onStop:
function
()
{}
//停止时回调函数
}
for
(var
p
in
options)
this.options[p]
=
options[p]
},
//获取id
$
:
function
(id)
{
return
typeof
id
===
"string"
?
document.getElementById(id)
:
id
},
//添加绑定事件
addHandler
:
function
(oElement,
sEventType,
fnHandler)
{
return
oElement.addEventListener
?
oElement.addEventListener(sEventType,
fnHandler,
false)
:
oElement.attachEvent("on"
+
sEventType,
fnHandler)
},
//删除绑定事件
removeHandler
:
function
(oElement,
sEventType,
fnHandler)
{
return
oElement.removeEventListener
?
oElement.removeEventListener(sEventType,
fnHandler,
false)
:
oElement.detachEvent("on"
+
sEventType,
fnHandler)
},
//绑定事件到对象
bind
:
function
(object,
fnHandler)
{
return
function
()
{
return
fnHandler.apply(object,
arguments)
}
}
}
//应用
window.onload
=
function
()
{
var
oBox
=
document.getElementById("box")
var
oTitle
=
oBox.getElementsByTagName("h2")[0]
var
oSpan
=
document.getElementsByTagName("span")[0]
var
oDrag
=
new
Drag(oBox,
{handle:oTitle,
limit:false})
var
aInput
=
document.getElementsByTagName("input")
//锁定范围接口
aInput[0].onclick
=
function
()
{
oDrag.limit
=
!oDrag.limit
this.value
=
oDrag.limit
?
"取消锁定范围"
:
"锁定范围"
}
//水平锁定接口
aInput[1].onclick
=
function
()
{
oDrag.lockX
=
!oDrag.lockX
this.value
=
oDrag.lockX
?
"取消水平锁定"
:
"水平锁定"
}
//垂直锁定接口
aInput[2].onclick
=
function
()
{
oDrag.lockY
=
!oDrag.lockY
this.value
=
oDrag.lockY
?
"取消垂直锁定"
:
"垂直锁定"
}
//锁定位置接口
aInput[3].onclick
=
function
()
{
oDrag.lock
=
!oDrag.lock
this.value
=
oDrag.lock
?
"取消锁定位置"
:
"锁定位置"
}
//开始拖拽时方法
oDrag.onStart
=
function
()
{
oSpan.innerHTML
=
"开始拖拽"
}
//开始拖拽时方法
oDrag.onMove
=
function
()
{
oSpan.innerHTML
=
"left:"
+
this.drag.offsetLeft
+
",
top:"
+
this.drag.offsetTop
}
//开始拖拽时方法
oDrag.onStop
=
function
()
{
oSpan.innerHTML
=
"结束拖拽"
}
}
</script>
</head>
<body>
<div
id="tool">
<input
type="button"
value="锁定范围"
/>
<input
type="button"
value="水平锁定"
/>
<input
type="button"
value="垂直锁定"
/>
<input
type="button"
value="锁定位置"
/>
</div>
<p>拖放状态：<span>未开始</span></p>
<div
id="box">
<h2
class="title"></h2>
</div>
</body>
</html>
希望本文所述对大家的JavaScript程序设计有所帮助。
