How can you use html tags in javascript?

Question

Back to Class 9 page »

Table of Contents Show

First, What Is JavaScript?
Including the JavaScript
The Script Tag
Using the script tag to include an external JavaScript file
JavaScript Files
Simple Demo of Including JavaScript
Other People's JavaScript
JavaScript Frameworks
JavaScript File Sizes
Answer: Use the concatenation operator (+)
Related FAQ
How does HTML work with JavaScript?
HOW include HTML code in JavaScript?

Including JavaScript in your page is a fairly simple process.

First, What Is JavaScript?

From the W3C Schools Site:

JavaScript was designed to add interactivity to HTML pages
JavaScript is a scripting language
A scripting language is a lightweight programming language
JavaScript is usually embedded directly into HTML pages
JavaScript is an interpreted language (means that scripts execute without preliminary compilation)
Everyone can use JavaScript without purchasing a license

Including the JavaScript

You can include JavaScript in your HTML in two ways:

Writing the code in your HTML
Including it as a link to an external file

For the most part, you will include the JavaScript as an external file.

The Script Tag

The <script> tag is what we use to includes our JavaScript. It's a lot like the <link> tag you've already been using to include your CSS files.

Here's a very basic snippet of JavaScript using the script tag. This JavaScript is written directly into our HTML page. It will call and alert box as soon as the page loads.

<script type="text/javascript">
  alert("This alert box was called with the onload event");
</script>

When using the script tag, we must always use the attribute name and value of type="text/javascript".

Using the script tag to include an external JavaScript file

To include an external JavaScript file, we can use the script tag with the attribute src. You've already used the src attribute when using images. The value for the src attribute should be the path to your JavaScript file.

<script type="text/javascript" src="path-to-javascript-file.js"></script>

This script tag should be included between the <head> tags in your HTML document.

JavaScript Files

JavaScript files are not HTML files or CSS files.

Always end with the js extension
Only include JavaScript

It's customary to put all JavaScript files in a folder called js on websites, like so:

Simple Demo of Including JavaScript

Here's a very simple demonstration of how to include an external JavaScript file into an HTML page.

Basic JavaScript Example

Other People's JavaScript

For this class you are not expected to write any actual JavaScript code. Lucky for you, many of people have already written lots of JavaScript and even allow you to use it for free.

JavaScript Frameworks

A Framework is basically a library of code for a certain language. Generally, the framework abstracts common tasks and makes it easier and faster for designers and developers to write their specific code. Frameworks don't really do anything by themselves, they just provide an easier platform for people to build on.

Common JavaScript Frameworks:

JQuery
Prototype
MooTools
script.aculo.us

Of these frameworks, JQuery is currently the most popular one. It's also the one you're most like to encounter being used as a buzz word.

JavaScript File Sizes

Many JavaScript files can tend to be rather large, which can slow down the load time of your page. Popular frameworks usually offer a "minified" version of their code. You should always use this version in your pages because it will have a smaller file size.

Back to Class 9 page »

Topic: JavaScript / jQueryPrev|Next

Answer: Use the concatenation operator (+)

The simple and safest way to use the concatenation operator (+) to assign or store a bock of HTML code in a JavaScript variable. You should use the single-quotes while stingify the HTML code block, it would make easier to preserve the double-quotes in the actual HTML code.

You also need to escape the single-quotes which appears inside the content of HTML block — just replace the ' character with \', as shown in the following example:

<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8">
<title>Store HTML Code in JavaScript Variable</title> 
</head> 
<body>
<div id="wrapper"></div>
<script>
// Storing HTML code block in a variable
var codeBlock = '<div class="content">' +
                    '<h2>This is a heading</h2>' +
                    '<p>This is a paragraph of text.</p>' +
                    '<p><strong>Note:</strong> If you don\'t escape "quotes" properly, it will not work.</p>' +
                '</div>';

// Inserting the code block to wrapper element
document.getElementById("wrapper").innerHTML = codeBlock
</script> 
</body>
</html>

Here are some more FAQ related to this topic: