#传统的过程式编写选项卡  ``` <style> #div1 div{ width: 200px; height: 200px; border: 1px #000 solid; display: none; } .active{ background: red; } </style> <script> window.onload = function(){ var oParent = document.getElementById('div1'); var aInput = oParent.getElementsByTagName('input'); var aDiv = oParent.getElementsByTagName('div'); for(var i=0; i<aInput.length; i++){ aInput[i].index = i; aInput[i].onclick = function(){ for(var j=0; j<aInput.length; j++){ aInput[j].className = ''; aDiv[j].style.display = 'none'; } this.className = 'active'; aDiv[this.index].style.display = 'block'; }; } }; </script> <div id="div1"> <input class="active" type="button" value="1"> <input type="button" value="2"> <input type="button" value="3"> <div style="display: block;">111</div> <div>222</div> <div>333</div> </div> ``` 先变型： 尽量不要出现函数嵌套函数 可以有全局变量 ``` var oParent = null; var aInput = null; var aDiv = null; window.onload = function(){ oParent = document.getElementById('div1'); aInput = oParent.getElementsByTagName('input'); aDiv = oParent.getElementsByTagName('div'); for(var i=0; i<aInput.length; i++){ aInput[i].index = i; aInput[i].onclick = change; } }; function change(){ for(var i=0; i<aInput.length; i++){ aInput[i].className = ''; aDiv[i].style.display = 'none'; } this.className = 'active'; aDiv[this.index].style.display = 'block'; } ``` 把onload中不是赋值的语句放到单独的函数中 ``` var oParent = null; var aInput = null; var aDiv = null; window.onload = function(){ oParent = document.getElementById('div1'); aInput = oParent.getElementsByTagName('input'); aDiv = oParent.getElementsByTagName('div'); init(); }; function init(){ for(var i=0; i<aInput.length; i++){ aInput[i].index = i; aInput[i].onclick = change; } } function change(){ for(var j=0; j<aInput.length; j++){ aInput[j].className = ''; aDiv[j].style.display = 'none'; } this.className = 'active'; aDiv[this.index].style.display = 'block'; } ```