如何检查元素在JavaScript中是否有任何子代（） _前端开发

该任务借助JavaScript查找一个元素是否具有子元素。我们将讨论几种技术。
方法：

选择父元素。
使用其中之一firstChild, childNodes.length, children.length属性, 以查找element是否具有子元素。
hasChildNodes()方法也可以用于查找父节点的子节点。

范例1：在这个例子中hasChildNodes()方法用于确定< div> 元件。

< !DOCTYPE HTML> < html > < head > < title > How to check if element has any children in JavaScript ? < / title > < / head > < body style = "text-align:center; " > < h1 style = "color:green; " > lsbin < / h1 > < div id = "div" > < p id = "GFG_UP" style = "font-size: 19px; font-weight: bold; " > < / p > < / div > < button onclick = "GFG_Fun()" > click here < / button > < p id = "GFG_DOWN" style = "color:green; font-size:24px; font-weight:bold; " > < / p > < script > var parentDiv = document.getElementById("div"); var el_up = document.getElementById("GFG_UP"); var el_down = document.getElementById("GFG_DOWN"); el_up.innerHTML = "Click on the button to check " + "whether element has children."; function GFG_Fun() { var ans = "Element < div > has no children"; if (parentDiv.hasChildNodes()) { ans = "Element < div > has children"; }el_down.innerHTML = ans; } < / script > < / body > < / html >

输出如下：
在单击按钮之前：

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【如何检查元素在JavaScript中是否有任何子代（）】单击按钮后：

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范例2：在这个例子中children.length属性用于确定< div> 元件。

< !DOCTYPE HTML> < html > < head > < title > How to check if element has any children in JavaScript ? < / title > < / head > < body style = "text-align:center; " > < h1 style = "color:green; " > lsbin < / h1 > < div id = "div" > < p id = "GFG_UP" style = "font-size: 19px; font-weight: bold; " > < / p > < / div > < button onclick = "GFG_Fun()" > click here < / button > < p id = "GFG_DOWN" style = "color:green; font-size:24px; font-weight:bold; " > < / p > < script > var parentDiv = document.getElementById("div"); var el_up = document.getElementById("GFG_UP"); var el_down = document.getElementById("GFG_DOWN"); el_up.innerHTML = "Click on the button to "+ "check whether element has children."; function GFG_Fun() { var ans = "Element < div > has no children"; if (parentDiv.children.length > 0) { ans = "Element < div > has children"; }el_down.innerHTML = ans; } < / script > < / body > < / html >

输出如下：
在单击按钮之前：