JavaScript is untyped language. This means that a JavaScript variable can hold a value of any data type. To declare variables in JavaScript, you need to use the var keyword. Whether it is a number or string, use the var keyword for declaration.Here’s how you can declare numbers in JavaScript −var points = 100; var rank = 5;ExampleYou can try to run the following code to learn how to declare number in JavaScript −                                

Before beginning with the difference, let’s learn what are Primitive Datatypes. Primitive defines immutable values and introduced recently by ECMAScript standard.JavaScript allows you to work with three primitive data types, Numbers, eg. 3, 310.20 etc.Strings of text e.g. "This text string" etc.Boolean e.g. true or false.JavaScript also defines two trivial data types, null and undefined, each of which defines only a single value. In addition to these primitive data types, JavaScript supports a composite data type known as the object.After datatypes, let us discuss about Objects:Objects In JavaScript, objects are considered a collection of properties. Identify properties using key values. It ... Read More

Inline JavaScript Code − If you are adding some JavaScript code in an HTML file without using the src tag then it is known as inline JavaScript code. That’s all you need to know.

The following are the difference between inline JavaScript and external file −External scriptsThe browser stores the external script once it is downloaded for the first time. If it is to be referenced again, then no additional download is needed.This reduces download time and size.The async and defer attributes have an effect. If these attributes are present the script will change the default behavior.Inline scriptsInline Scripts are executed immediately.It gets loaded instantly and there is no need to trigger another request.The async and defer attributes has no effect.Inline Scripts are more useful for server-side dynamic rendering.Read More

To avoid multiple server requests, group your JavaScript files into one. Whatever you use for performance, try to minify JavaScript to improve the load time of the web page.If you are using single page application, then group all the scripts in a single file.If you are using multiple files, then minify all of your scripts and separate them into categories.example - Place JavaScript to be used in every page. This can be the core script of the file. - Place your plugins hereRest, add other scripts in a JavaScript file. It’s good to maintain it in different files.Read More

Page load time gets affected with JavaScript files and code. If you are not optimizing JavaScript files then the page load time will increase, which shouldn’t happen. Minify the JavaScript code to decrease the page load time.Also, cache JavaScript file for better results. For better performance, use inline and external JavaScript properly. Try to use external JavaScript file if you want to add the same script in multiple pages.External scriptsThe browser stores the external script once it is downloaded for the first time. If it is to be referenced again, then no additional download is needed.This reduces download time and ... Read More

To use the same JavaScript in more than one page, add the js code in an external JavaScript file. Let’s say the following demo.js is our external JavaScript file −function display() {    alert("Hello World!"); }Now add the external JavaScript file to the following HTML web page. In the same way, you can add it to multiple content page.                                          

Let’s say the following line we have in our HTML −Here the browser identifies inline JavaScript by detecting onclick, even when tag wasn’t available.The following are some of the suggestions for using inline JavaScripts −You should consider inline script elements such as ...) if the script only to be used for a single page.Do not use event attributes such as onclick="...", and bind event handlers using JavaScript.Use external script elements such as ) for most scripts, especially if reused between pages.

JavaScript’s automatic semicolon insertion (ASI) is to insert missing semicolons. The following statements are affected by automatic semicolon insertion −empty statement var statement expression statement do-while statement continue statement break statement return statement  throw statementThe rules are in the following specification −When, as a Script or Module is parsed from left to right: A token is encountered that is not allowed by any production of the grammar, then a semicolon is automatically inserted before the offending token only if one or more of the following conditions becomes true −Offending token is }.Previous token is ) and the inserted semicolon would ... Read More

It’s always a good practice to add jQuery code in footer i.e. just before the closing tag. If you have not done that, then use the defer attribute.Use defer attribute so the web browser knows to download your scripts after the HTML downloaded −The defer attribute is used to specify that the script execution occurs when the page loads. It is useful only for external scripts and is a boolean attribute.ExampleThe following code shows how to use the defer attribute −                 The external file added will load later, since we're using defer