Multi-level linkage can be run by directly copying the code. Pure front-end without back-end and database. The code compression package is included at the bottomhtml PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"><br>
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<meta>
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<title>JavaScript 自定义多级联动下拉菜单</title>
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<script>var $ = function(id) {<br />
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return "string" == typeof id ? document.getElementById(id) : id;<br />
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};<br />
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function addEventHandler(oTarget, sEventType, fnHandler) {<br />
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if (oTarget.addEventListener) {<br />
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oTarget.addEventListener(sEventType, fnHandler, false);<br />
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} else if (oTarget.attachEvent) {<br />
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oTarget.attachEvent("on" + sEventType, fnHandler);<br />
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} else {<br />
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oTarget["on" + sEventType] = fnHandler;<br />
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}<br />
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};<br />
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function Each(arrList, fun) {<br />
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for (var i = 0,<br />
len = arrList.length; i < len; i++) {<br />
fun(arrList[i], i);<br />
}<br />
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};<br />
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function GetOption(val, txt) {<br />
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var op = document.createElement("OPTION");<br />
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op.value = val;<br />
op.innerHTML = txt;<br />
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return op;<br />
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};<br />
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var Class = {<br />
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create: function() {<br />
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return function() {<br />
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this.initialize.apply(this, arguments);<br />
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}<br />
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}<br />
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Object.extend = function(destination, source) {<br />
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for (var property in source) {<br />
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destination[property] = source[property];<br />
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}<br />
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return destination;<br />
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}<br />
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var CascadeSelect = Class.create();<br />
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CascadeSelect.prototype = {<br />
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//select集合，菜单对象<br />
initialize: function(arrSelects, arrMenu, options) {<br />
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if (arrSelects.length <= 0 || arrMenu.lenght <= 0) return; //菜单对象<br />
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var oThis = this;<br />
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this.Selects = []; //select集合<br />
this.Menu = arrMenu; //菜单对象<br />
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this.SetOptions(options);<br />
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this.Default = this.options.Default || [];<br />
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this.ShowEmpty = !!this.options.ShowEmpty;<br />
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this.EmptyText = this.options.EmptyText.toString();<br />
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//设置Selects集合和change事件<br />
Each(arrSelects,<br />
function(o, i) {<br />
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addEventHandler((oThis.Selects[i] = $(o)), "change",<br />
function() {<br />
oThis.Set(i);<br />
});<br />
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});<br />
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this.ReSet();<br />
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},<br />
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//设置默认属性<br /> SetOptions: function(options) {<br />
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This.options = { //Default value<br />
Default: [],<br />
//Default value (in order)<br />
ShowEmpty: false,<br />
// Whether to display the empty value (located in the first one) <br />
EmptyText: "Please select" //Empty value display text (valid when ShowEmpty is true)<br />
};<br />
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Object.extend(this.options, options || {});<br />
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},<br />
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//Initialize select<br />
ReSet: function() {<br />
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This.SetSelect(this.Selects[0], this.Menu, this.Default.shift());<br />
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This.Set(0);<br />
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},<br />
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Set: function(index) {<br />
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var menu = this.Menu<br />
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//The first select does not need to be processed, so it starts from 1<br />
Len = this.selects.length; i & lt; len; I ++) {<br />
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If (menu.length > 0) {<br />
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var value = this.Selects[i - 1].value;<br />
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If (value != "") {<br />
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function(o) {<br />
If (o.val == value) {<br />menu = o.menu || [];<br />
});<br />
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menu = [];<br />
}<br />
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If (i > index) {<br />
This.SetSelect(this.Selects[i], menu, this.Default.shift());<br />
}<br />
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} Else {s
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This.SetSelect(this.Selects[i], [], "");<br />
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}<br />
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This.Default.length = 0;<br />
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},<br />
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//select settings<br />
SetSelect: function(oSel, menu, value) {<br />
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oSel.options.length = 0;<br />
oSel.disabled = false;<br />
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If (this.ShowEmpty) {<br />
oSel.appendChild(GetOption("", this.EmptyText));<br />
}<br />
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If (menu.length <= 0) {<br />
oSel.disabled = true;<br /> return;<br />
}<br />
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Each(menu,<br />
function(o) {<br />
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var op = GetOption(o.val, o.txt ? o.txt: o.val);<br />
op.selected = (value == op.value);<br />
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oSel.appendChild(op);<br />
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});<br />
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},<br />
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//添加菜单<br />
Add: function(menu) {<br />
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this.Menu[this.Menu.length] = menu;<br />
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this.ReSet();<br />
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},<br />
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//删除菜单<br />
Delete: function(index) {<br />
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if (index < 0 || index >= this.Menu.length) return;<br />
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for (var i = index,<br />
len = this.Menu.length - 1; i < len; i++) {<br />
this.Menu[i] = this.Menu[i + 1];<br />
}<br />
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this.Menu.pop()<br />
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this.ReSet();<br />
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}<br />
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};<br />
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window.onload = function() {<br />
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var menu = [<br />
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{<br />
'val': '1',<br />
'txt': 'value'<br />
},<br />
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{<br />
'val': '2 ->',<br /> 'menu': [<br />
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{<br />
'val': '2_1'<br />
},<br />
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{<br />
'val': '2_2'<br />
}<br />
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]<br />
},<br />
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{<br />
'val': '3 ->',<br />
'menu': [<br />
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{<br />
'val': '3_1 ->',<br />
'menu': [<br />
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{<br />
'val': '3_1_1'<br />
},<br />
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{<br />
'val': '3_1_2'<br />
}<br />
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]<br />
},<br />
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{<br />
'val': '3_2'<br />
}<br />
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]<br />
},<br />
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{<br />
'val': '4 ->',<br />
'menu': [<br />
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{<br /> 'val': '4_1 ->',<br />
'menu': [<br />
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{<br />
'val': '4_1_1 ->',<br />
'menu': [<br />
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{<br />
'val': '4_1_1_1'<br />
}<br />
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]<br />
}<br />
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]<br />
}<br />
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]<br />
}<br />
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];<br />
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var sel = ["sel1", "sel2", "sel3", "sel4", "sel5"];<br />
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var val = ["3 ->", "3_1 ->", "3_1_2"];<br />
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var cs = new CascadeSelect(sel, menu, {<br />
Default: val<br />
});<br />
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$("btnA").onclick = function() {<br />
cs.ShowEmpty = !cs.ShowEmpty;<br />
}<br />
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$("btnB").onclick = function() {<br />
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cs.Add(<br />
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{<br />
'val': '5 ->',<br />
'menu': [<br />
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{<br /> 'val': '5_1 ->',<br />
'menu': [<br />
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{<br />
'val': '5_1_1 ->',<br />
'menu': [<br />
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{<br />
'val': '5_1_1_1 ->',<br />
'menu': [<br />
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{<br />
'val': '5_1_1_1_1'<br />
}<br />
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]<br />
}<br />
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]<br />
}<br />
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]<br />
}<br />
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]<br />
}<br />
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)<br />
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}<br />
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$("btnC").onclick = function() {<br />
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cs.Delete(3)<br />
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}<br />
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}</script><br>
<style>.sel select{ width:100px;}</style>
<br> <br>
<div>
<br>
<select></select><br>
<select></select><br>
<select></select><br>
<select></select><br>
<select></select><br>
</div>
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<br><br>
<div>
<br>
<input><br>
<input><br>
<input>
</div>
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<br>
duoji.zip
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