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：
单击按钮后：
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：
单击按钮后：
