Introduction to Javascript : A Beginner's Guide
Motunrayo Joseph
Software QA Engineer | Manual, Automation & Performance Testing | Product Delivery | Passionate about improving software development quality process | API Technical Writer | Sharing insights on QA testing
Table of Contents
Brief History of JavaScript
JavaScript was created by Brendan Eich in April of 1995. At that time, he participated in developing a web browser for a company called Netscape. He was given directions to develop and program a working prototype of a browser-friendly programming language in only 10 days.
He needed to create a language that would appeal to novice programmers, similar to Microsoft Visual Basic. He only had a 10-day timeframe due to Netscape needing to release its browser, which was in competition with Microsoft at the time.
At first, JavaScript was not as robust as it is now because it was primarily created to enhance web pages with interaction and animation. It wasn't until 2005 that JavaScript started being used on all websites with the release of jQuery and AJAX.
After Google released its updated Chrome browser, Facebook began attracting a larger online audience. JavaScript started expanding to meet the goals of these massive internet corporations.
Browsers started creating APIs that were accessible in JavaScript. JavaScript has the capability to gather data like IP addresses and geographic locations from the browser, giving internet companies more control to tailor the features of their websites. Then another advancement occurred to enhance the capabilities of JavaScript even further.
In 2009, Node.js, a server-side environment, was launched, enabling JavaScript to operate on the server side just like PHP, Java, Python, and Ruby. It also enabled developers to build complete web applications using JavaScript for both the front and backend. Today, JavaScript is capable of powering applications on the web, desktop, and mobile.
In this article introducing JavaScript, you will gain insight into JavaScript, the foundation of web development, and grasp the purpose and applications of this versatile language in different industries.
What is Javascript?
JavaScript is a versatile, sophisticated coding language primarily used for creating interactive and dynamic web pages. It has a crucial role in modern web design, enabling developers to create engaging and interactive user interfaces like complex animations, clickable buttons, popup menus, etc.
Numerous web browsers utilize JavaScript as a scripting language for performing interactive tasks online. Whenever you encounter a click-to-show dropdown menu, additional content inserted into a page, and dynamically shifting colors of elements on a page, you are witnessing the impacts of JavaScript.
How JavaScript Makes Things Dynamic.
To gain a comprehensive understanding of JavaScript, it is essential to have a fundamental knowledge of HTML and CSS.
Basically, HTML defines the structure of your webpage and its contents, while CSS specifies different styles for the content displayed on the website document. JavaScript, the third key technology in web development, defines the functionality of HTML and CSS.
Before we explore how JavaScript accomplishes these tasks, let's first examine a brief example.
Check out this Codepen: https://codepen.io/Dillion/full/XWjvdMG
Note: When text is entered in the input field on Codepen, it will be displayed on the screen. This is achievable through the use of JavaScript. This cannot be achieved with HTML, CSS, or a combination of both.
Key concepts and features of JavaScript:
1. Variables
When programming, a variable is just a name assigned to a value that can be retrieved later. A variable is like a tag that can be attached to a value, allowing you to access the value through the tag. Think of it like the price tag on the products you get at the supermarket.
Variables hold data values that can be utilized and modified in your program using:
Examine an example below.
var name = 'John'; // Declares a variable that can be reassigned
let age = 30; // Declares a block-scoped variable that can be reassigned
const birthYear = 1990; // Declares a block-scoped constant variable
2. Data Types
Data types are basically descriptions of various kinds of data recognized by a programming language. A data type includes information on what actions are allowed and not allowed with the data.
JavaScript includes a range of data types like :
Examine an example below.
let num = 5; // Number
let text = "Hello World"; // String
let isTrue = true; // Boolean
let items = [1, 2, 3]; // Array
let person = { // Object
firstName: "John",
lastName: "Doe"
};
3. Functions
Functions are blocks of code designed to perform a particular task that can be used multiple times.
For instance, the String() type casting function is utilized to change data from a different type to a string.
Here's a detailed look at functions in JavaScript:
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Examine an example below.
// Function Declaration
function greet(name) {
return "Hello, " + name;
}
// Function Expression
const greet = function(name) {
return "Hello, " + name;
};
// Arrow Function
const greet = (name) => "Hello, " + name;
console.log(greet("Alice")); // Output: Hello, Alice
4. Control Structures
A computer program typically has to consider numerous conditions that may occur during its operation.
This is comparable to the way a person makes choices in their life. As an illustration, do you have enough funds to pay for the trip to Paris? If the answer is yes, proceed. If not, then start saving more money!
This is when control flow enters the picture. Control structures in programming languages permit the execution of specific code based on varying conditions that may occur.
Utilizing control structures enables you to establish various routes that a program may follow depending on the conditions within the program.
JavaScript contains different control structures, like the following:
Examine an example below.
let num = 10;
if (num > 5) {
console.log("Number is greater than 5");
} else {
console.log("Number is 5 or less");
}
for (let i = 0; i < 5; i++) {
console.log(i); // Output: 0 1 2 3 4
}
5. Objects
An object is a distinct data type that allows you to hold various values, just like an array. It stores data in a key-value pair format, whereas an array stores data as a list of items.
Creating Objects:
Examine an example below.
let person = {
firstName: "John",
lastName: "Doe",
age: 30,
greet: function() {
return "Hello, " + this.firstName;
}
};
console.log(person.firstName); // Output: John
console.log(person.greet()); // Output: Hello, John
Examine an example below.
function Person(firstName, lastName, age) {
this.firstName = firstName;
this.lastName = lastName;
this.age = age;
this.greet = function() {
return "Hello, " + this.firstName;
};
}
let john = new Person("John", "Doe", 30);
console.log(john.firstName); // Output: John
console.log(john.greet()); // Output: Hello, John
Benefits of JavaScript
Once you are familiar with the key concepts and features of Javascript, we can now explore how to begin using it.
How to begin your JavaScript journey.
1. Setting Up Your Environment: To start coding JavaScript, you only need:
2. Explore JavaScript further by:
Final Words: JavaScript is a powerful and versatile language that is essential for modern web development. Learning JavaScript enables you to develop interactive websites, construct web applications, and improve the user experience online. Begin by mastering the fundamentals, consistently practice, and dive into more complex subjects as you gain confidence in the language. Happy coding!
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Motunrayo Joseph | Technical Writer at Product Tribe.
Technical Writer || Documentation Engineer || Web3 Advocate || I help Web3 and SaaS founders communicate with their audience through concise technical documents.
7 个月Very informative