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js中用tagname和id获取元素的3种方法

2024-10-02 02:24:02   217人阅读

<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>3种用tagname和id获取元素的方法</title>
<style>
body{
    margin: 0;
}
ul{
    margin: 0;
    padding: 0;
    list-style: none;
}
h1{
    margin: 0;
}
</style>
</head>
<body>
<div class="box" id="box">
    <h1 class="box-tit">分类名称</h1>
    <ul class="box-list" id="box-list">
        <li class="box-listI">
            <input class="box-listI-input">
            <button>保存</button>
            <button>取消</button>
        </li>
        <li class="box-listI">
            <input class="box-listI-input">
            <button>保存</button>
            <button>取消</button>
        </li>
        <li class="box-listI">
            <input class="box-listI-input">
            <button>保存</button>
            <button>取消</button>
        </li>
    </ul>
</div>
<script>
//[1]整体法，先获取所有的元素，再通过ai+-b的方法来算出需要的元素
var oList = document.getElementById(‘box-list‘);
var aInput = oList.getElementsByTagName(‘input‘);
var aBtn =oList.getElementsByTagName(‘button‘);
for(var i = 0; i < aBtn.length; i++){
    aBtn[i].index = i;
}
for(var i = 0; i < aInput.length; i++){
    //确定按钮
    aBtn[2*i].onclick = function(){
        aInput[this.index/2].disabled = true;
    }
    //取消按钮
    aBtn[2*i+1].onclick = function(){
        aInput[(this.index-1)/2].disabled = false;
        aInput[(this.index-1)/2].value =http://www.mamicode.com/ ‘‘;
        console.log(1);
    }
}
//[2]数组法，在全局环境下建立空数组，遇到需要循环的结构时，在循环中获取元素，并放入数组
var oList = document.getElementById(‘box-list‘);
var aIn = oList.getElementsByTagName(‘li‘);
var aInput = [];
var aBtnY = [];
var aBtnX = [];
for(var i = 0; i < aIn.length; i++){
    aInput[i] = aIn[i].getElementsByTagName(‘input‘)[0];
    aBtnY[i] = aIn[i].getElementsByTagName(‘button‘)[0];
    aBtnX[i] = aIn[i].getElementsByTagName(‘button‘)[1];
    aBtnY[i].index = aBtnX[i].index = i;
    //确定按钮
    aBtnY[i].onclick = function(){
        aInput[this.index].disabled = true;
    }
    //取消按钮
    aBtnX[i].onclick = function(){
        aInput[this.index].disabled = false;
        aInput[this.index].value =http://www.mamicode.com/ ‘‘;
        console.log(2);
    }  
}
//[3]函数法，遇到相同的几组元素时，只操作一组元素，并用函数传参来实现所有的效果
var oList = document.getElementById(‘box-list‘);
var aIn = oList.getElementsByTagName(‘li‘);
function fn(i){
    var oInput  = aIn[i].getElementsByTagName(‘input‘)[0];
    var oBtnY = aIn[i].getElementsByTagName(‘button‘)[0];
    var oBtnX = aIn[i].getElementsByTagName(‘button‘)[1];
    //确定按钮
    oBtnY.onclick = function(){
        oInput.disabled = true;
    }
    //取消按钮
    oBtnX.onclick = function(){
        oInput.disabled = false;
        oInput.value =http://www.mamicode.com/ ‘‘;
        console.log(3);
    }      
}
for( var i = 0; i < aIn.length; i++){
    fn(i);
}
</script>
</body>
</html>

js中用tagname和id获取元素的3种方法


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