javascript 三级下拉选择菜单Levels对象_导航菜单

JavaScript：

复制代码 代码如下:

HTML：

复制代码 代码如下:

演示代码：

<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1"> <title>Untitled Document</title> <script type="text/javascript"> var level1 = ["Beijing", "GuangZhou", "ShangHai"]; var level2 = [["ZhaoYang", "TianTan", "GuGong"], ["Tianhe", "Panyu"], ["PuDong", "PuXi"]]; var level3 = [[["TianShan", "HuangShan"], ["TianTan1", "TianTan2"], ["GuGong1", "GuGong2", "GuGong3", "GuGong4"]], [["TianHe1", "TianHe2"], ["PanYu1", "PanYu2"]], [["PuDong1", "PuDong2"], ["PuXi1", "PuXi2"]]]; var Levels = { fL: null,//用存储各级select的DOM引用 sL: null, tL: null, l1: null, l2: null, l3: null, $: function(id){ return (typeof id == "object") ? id : document.getElementById(id); }, init: function(fID, sID, tID, l1, l2, l3){ this.fL = this.$(fID); this.sL = this.$(sID); this.tL = this.$(tID); this.l1 = l1; this.l2 = l2; this.l3 = l3; this.fL.options.add(new Option("Select",-1));//给一级菜单添加一个"select"标志 for (var i = 0; i < l1.length; i++) { var item = new Option(l1[i], i); this.fL.options.add(item); } this.doLev2(); //调用doLev2函数，处理二级菜单 this.doLev3(); //调用doLev3函数，处理三级菜单 }, removeSTL: function(){ //用于删除第二、三级的菜单项 this.sL.options.length = 0; this.tL.options.length = 0; }, removeTL: function(){ //用于删除第三级的菜单项 this.tL.options.length = 0; }, doLev2: function(){ //处理二级菜单 var that = this; this.fL.onchange = function(){ that.removeSTL(); //删除旧second的select if (that.fL.selectedIndex == 0) { that.removeSTL(); // //删除旧second的select } else { that.sL.options.add(new Option("Select", -1)); //给二级菜单添加一个"select"标志 //获取第二级所需的数组 var items = that.l2[that.fL.selectedIndex - 1]; for (var i = 0; i < items.length; i++) { //添加第二级的新select项 var item = new Option(items[i], i); that.sL.options.add(item); } } } }, doLev3: function(){ //处理三级菜单 var that = this; this.sL.onchange = function(){ that.removeTL(); //删除旧third的select if (that.sL.selectedIndex == 0) { that.removeTL(); //删除旧third的select } else { that.tL.options.add(new Option("Select", -1)); //给三级菜单添加一个"select"标志 //获取第三级所需的数组 var items = that.l3[that.fL.selectedIndex - 1][that.sL.selectedIndex - 1]; for (var i = 0; i < items.length; i++) { //添加第三级的新select项 var item = new Option(items[i], i); that.tL.options.add(item); } } } } } onload = function(){ Levels.init("first", "second", "third", level1,level2,level3); //调用Levels的init方法 } </script> <form> <select id="first"> </select> <select id="second"> </select> <select id="third"> </select> </form>
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