Modern browsers use JavaScript. JavaScript can manipulate both CSS and HTML contents of a webpage. JavaScript allows for the use of functions.

Functions are the fundamental building blocks in JavaScript. A function is a set of statements that perform a specific predefined task and returns a value. In this article we are going to learn how to call JavaScript functions in HTML.

A Function consists of the three basic components:

  • The name of the function.
  • Parameters, enclosed in parenthesis and comma separated.
  • The statements that define the function, enclosed in curly brackets.

For Example:

We can call the following function in JavaScript by simply using the name and passing the parameters:

We can see the result in the browsers console:

We can also the function from the HTML file by using script tags:

The ‘jscode.js’ file contains the definition of the multiplication function.

We can bind a function to an event, so that the function gets called whenever that event occurs.

For example:

We define another function

We now change the HTML to add a button, which when clicked triggers the ‘alert_multiplication’ function:

The webpage now displays a button, which when clicked shows a popup:

We can use event attributes to call functions whenever a user clicks a button, a key is pressed, the mouse hovers over an element and etc.

How do I call a JavaScript script?

To execute JavaScript in a browser you have two options — either put it inside a script element anywhere inside an HTML document, or put it inside an external JavaScript file (with a . js extension) and then reference that file inside the HTML document using an empty script element with a src attribute.

How do I run a script in HTML?

The “script” tag

JavaScript programs can be inserted almost anywhere into an HTML document using the <script> tag. You can run the example by clicking the “Play” button in the right-top corner of the box above. The <script> tag contains JavaScript code which is automatically executed when the browser processes the tag.

What is script in HTML?

The HTML <script> tag is used to define a client-side script (JavaScript). The <script> element either contains script statements, or it points to an external script file through the src attribute. Common uses for JavaScript are image manipulation, form validation, and dynamic changes of content.

Is JavaScript free to install?

For those want to learn to program, one of the biggest advantages of JavaScript is that it is all free. You don’t need to pay for anything to get started.

How do I get JavaScript?

Chrome™ Browser – Android™ – Turn JavaScript On / Off
  1. From a Home screen, navigate: Apps icon > (Google) > Chrome .
  2. Tap the Menu icon.
  3. Tap Settings.
  4. From the Advanced section, tap Site settings.
  5. Tap JavaScript.
  6. Tap the JavaScript switch to turn on or off .

How do I open JavaScript in chrome?

Activate JavaScript in Google Chrome
  1. Open Chrome on your computer.
  2. Click. Settings.
  3. Click Privacy and security.
  4. Click Site settings.
  5. Click JavaScript.
  6. Turn on Allowed (recommended).

How do I check if JavaScript is enabled?

  1. go to Tools.
  2. then Internet Options
  3. select the Security tab.
  4. press the Custom Level button.
  5. scroll down to Scripting.
  6. enable Active Scripting.

How do I enable Java in Chrome?

At the bottom click the link called Show advanced settings Under the Privacy, section click on Content settings Scroll down to the Plug-ins section and click on Disable individual plug-ins. Look for the Java plugin and click on the Disable link to turn off or the Enable link to turn on.

How do I read HTML code?

  1. Open your browser and navigate to the page for which you wish to view the HTML.
  2. Right-click on the page to open the right-click menu after the page finishes loading.
  3. Click the menu item that allows you to view the source.
  4. When the source page opens, you’ll see the HTML code for the full page.

How do I open HTML code?

Open the Google Chrome browser on your Android phone or tablet. Open the web page whose source code you’d like to view. Tap once in the address bar and move the cursor to the front of the URL. Type view-source: and tap Enter or Go.

How do I display HTML code in browser?

You can show HTML tags as plain text in HTML on a website or webpage by replacing < with &lt; or &60; and > with &gt; or &62; on each HTML tag that you want to be visible. Ordinarily, HTML tags are not visible to the reader on the browser.

How do I write HTML code?

HTML Editors
  1. Step 1: Open Notepad (PC) Windows 8 or later:
  2. Step 1: Open TextEdit (Mac) Open Finder > Applications > TextEdit.
  3. Step 2: Write Some HTML. Write or copy the following HTML code into Notepad:
  4. Step 3: Save the HTML Page. Save the file on your computer.
  5. Step 4: View the HTML Page in Your Browser.

Why is HTML code showing in browser?

That would be caused by the server being misconfigured, and sending an incorrect MIME type telling the browser that the page is plain text instead of HTML. Since Firefox follows the standards correctly (unlike some other browsers), it hence displays it as plain text, like it’s supposed to do in this case.

Why my HTML code is not working?

Here’s a list of some of the reasons code doesn’t work: Forgot to clear the browser cache: You may make CSS changes and think they don’t work when they actually do because the browser is actually displaying an older version of pages which include the older code. Clear your browser cache to make sure.

How do you make a doctype in HTML?

All HTML documents must start with a <! DOCTYPE> declaration. The declaration is not an HTML tag. It is an “information” to the browser about what document type to expect.