DOM节点添加，删除，警报 [英] DOM Nodes Adding, Deleting, Alerts
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问题描述
在这里有些迷失了，我不确定如何实现，我已经完成了HTML和CSS，但是不确定如何在JS中实现。
So a little lost here, I'm not sure how to approach this, I've done the HTML and CSS but not sure how to do it in JS.
我的HTML：
<!doctype html>
<html lang="en">
<head>
<title> Task 1 </title>
<meta charset="utf-8">
<script src="DomNodes.js"></script>
<style>
#output {
border: blue 5px solid;
padding: 10px;
margin-bottom: 10px;
margin-top: 10px;
width: 50%;
}
#output p {
padding:10px;
border: black 1px dashed;
}
</style>
</head>
<body>
<h2> TASK 3 - Creating, Appending and Deleting Nodes in the DOM Tree </h2>
<p> Type in text below, click add to add as paragraph. <button id="add"> ADD </button> </p>
<textarea id ="input" rows="10" cols="60">
</textarea><br>
<button id="delete">Delete Last Paragraph</button>
<br><br>
<h2> Added Paragraphs </h2>
<div id="output">
</div>
</body>
</html>
推荐答案
这是很少解释的代码
<!doctype html>
<html lang="en">
<head>
<title> Task 1 </title>
<meta charset="utf-8">
<!--<script src="DomNodes.js"></script>-->
<script>
function myFunction() {
//get input user
var userInput=document.getElementById("input").value;
//clean text area
document.getElementById("input").value="";
//create paragraph
var para = document.createElement("p");
//assign value ->user input
var node = document.createTextNode(userInput);
//assign text at paragraph
para.appendChild(node);
//assign paragraph at div tag
var element = document.getElementById("output");
element.appendChild(para);
}
function remove_LastChild() {
//get div output
var select = document.getElementById('output');
//control if there are child into output div
if (select.childElementCount>0){
//select last paragraph and remove it
select.removeChild(select.lastChild);
}
else{
alert("Tehere are not paragraph!");
}
}
</script>
<style>
#output {
border: blue 5px solid;
padding: 10px;
margin-bottom: 10px;
margin-top: 10px;
width: 50%;
}
#output p {
padding:10px;
border: black 1px dashed;
}
</style>
</head>
<body>
<h2> TASK 3 - Creating, Appending and Deleting Nodes in the DOM Tree </h2>
<p> Type in text below, click add to add as paragraph. <button id="add" onclick="myFunction()"> ADD </button> </p>
<textarea id ="input" rows="10" cols="60">
</textarea><br>
<button id="delete" onclick="remove_LastChild()">Delete Last Paragraph</button>
<br><br>
<h2> Added Paragraphs </h2>
<div id="output">
</div>
</body>
</html>
我希望这对您有帮助
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