Nigiri Nigiri - 5 months ago 10
HTML Question

The difference between 'innerHTML' and 'appendChild'

Watching the number of nodes in Chrome DevTools, I'm wondering what the difference in the dom tree after clicking Button1 and it after clicking Button2.



index.html

<html>
<head>
<script src="./js/main.js" type="text/javascript" charset="utf-8"></script>
<link rel="stylesheet" href="style/default.css">
</head>
<body>
<div id="buttons">
<div class="button" id="button1">Execute1</div>
<div class="button" id="button2">Execute2</div>
</div>
<div id="main"></div>
<div id="main2"></div>
</body>
</html>


main.js

document.addEventListener( "DOMContentLoaded", function() {
var button1 = document.getElementById('button1');
button1.addEventListener('click', function() {
document.getElementById('main').innerHTML += '<div>hello</div>';
});

var button2 = document.getElementById('button2');
button2.addEventListener('click', function() {
var div = document.createElement('div');
div.appendChild(document.createTextNode('hello2'));
document.getElementById('main2').appendChild(div);
});
} );


default.css

#buttons {
display:-webkit-flex;
align-items: center;
}

.button {
height: 30px;
width: 100px;
margin: 5px;
background-color: #0080C0;
color: #FFFFFF;
display:-webkit-flex;
align-items: center;
justify-content: center;
cursor: pointer;
}


When I click the Button1, the number of nodes is incremented by 4.

But when I click the button2, the number of nodes is incremented by 2.

Be incrementing by 2 makes sense for me as they could be a 'div' element and a text node 'hello2'.

But clicking the Button1, what other nodes be appended?


enter image description here

Answer

Using appendChild adds a new DOM element to the end of the parent node.

Using innerHTML += takes the existing DOM content of the parent node, serialises it to HTML in a string, adds some more HTML to the end of the string, erases the existing elements in the parent node, generates DOM elements from that string, then appends the new nodes to the parent node.

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