Skip to main content
Practice

JavaScript Summary

JavaScript is an essential programming language in web development, often referred to as the brain of web pages.

Let's briefly summarize the core concepts of JavaScript.


1. Variables​

Containers for storing data. Stored data can be of various types such as numbers, strings, booleans, objects, etc.

Variable declaration with the let keyword
let name = 'CodeFriends';

2. Functions​

Reusable blocks of code that perform specific tasks.

Declare greet function
function greet(userName) {
  console.log('Hello, ' + userName + '!');
}

greet('CodeFriends'); // "Hello, CodeFriends!" output

3. Conditional Statements​

Execute different code based on certain conditions.

if-else conditional statement
if (name === 'CodeFriends') {
  console.log('Hello, CodeFriends!');
} else {
  console.log('Hello, Guest!');
}

4. Loops​

Repeat a block of code multiple times based on certain conditions.

for loop
for (let i = 0; i < 5; i++) {
  console.log(i); // Outputs 0 to 4
}

5. Objects​

Collections of related data and/or functionality. These are often referred to as properties (keys).

person object
const person = {
  name: 'CodeFriends', // name property, string value
  age: 25, // age property, number value
  greet: function () { // greet property, function value
    console.log('Hello, ' + this.name + '!');
  },
};

person.greet(); // "Hello, CodeFriends!" output

6. Events​

Interactions on a web page such as button clicks, form submissions, page loads, etc.

Detect button click event
let button = document.querySelector('button');

// Button click event listener
button.addEventListener('click', function () {
  alert('You clicked the button!');
});

Want to learn more?

Join CodeFriends Plus membership or enroll in a course to start your journey.