Math.random() Math.random() returns a random number between 0 (inclusive), and 1 (exclusive): Example Math.random(); // returns a random number Try it Yourself » Math.random() always returns a number lower than 1. JavaScript Random Integers Math.random() used with Math.floor() can be used to return random integers. Example Math.floor(Math.random() * 10); // returns a random integer from 0 to […]
JavaScript arrays are used to store multiple values in a single variable. Example var cars = [“Saab”, “Volvo”, “BMW”]; Try it Yourself » What is an Array? An array is a special variable, which can hold more than one value at a time. If you have a list of items (a list of car names, for example), storing […]
JavaScript strings are used for storing and manipulating text. JavaScript Strings A JavaScript string is zero or more characters written inside quotes. Example var answer = “It’s alright”; var answer = “He is called ‘Johnny’”; var answer = ‘He is called “Johnny”‘; Try it Yourself » String Length The length of a string is found in the built in property length: Example […]
Scope determines the accessibility (visibility) of variables. JavaScript Function Scope In JavaScript there are two types of scope: Local scope Global scope JavaScript has function scope: Each function creates a new scope. Scope determines the accessibility (visibility) of these variables. Variables defined inside a function are not accessible (visible) from outside the function. Local JavaScript […]
Real Life Objects, Properties, and Methods In real life, a car is an object. A car has properties like weight and color, and methods like start and stop: Object Properties Methods car.name = Fiat car.model = 500 car.weight = 850kg car.color = white car.start() car.drive() car.brake() car.stop() All cars have the same properties, but the property values differ from car to car. All […]
A JavaScript function is a block of code designed to perform a particular task. A JavaScript function is executed when “something” invokes it (calls it). Example function myFunction(p1, p2) { return p1 * p2; // The function returns the product of p1 and p2 } Try it Yourself » JavaScript Function Syntax A JavaScript function is defined […]
JavaScript Assignment Operators Assignment operators assign values to JavaScript variables. Operator Example Same As = x = y x = y += x += y x = x + y -= x -= y x = x – y *= x *= y x = x * y /= x /= y x = x […]
Example Assign values to variables and add them together: var x = 5; // assign the value 5 to x var y = 2; // assign the value 2 to y var z = x + y; // assign the value 7 to z (x + y) Try it Yourself » The assignment operator (=) assigns a value to a variable. Assignment var x = 10; Try […]
JavaScript comments can be used to explain JavaScript code, and to make it more readable. JavaScript comments can also be used to prevent execution, when testing alternative code. Single Line Comments Single line comments start with //. Any text between // and the end of the line will be ignored by JavaScript (will not be […]
The <script> Tag In HTML, JavaScript code must be inserted between <script> and </script> tags. Example <script> document.getElementById(“demo”).innerHTML = “My First JavaScript”; </script> Try it Yourself » Old JavaScript examples may use a type attribute: <script type=”text/javascript”>. The type attribute is not required. JavaScript is the default scripting language in HTML. JavaScript Functions and Events A JavaScript function is […]
This page contains some examples of what JavaScript can do. JavaScript Can Change HTML Content One of many JavaScript HTML methods is getElementById(). This example uses the method to “find” an HTML element (with id=”demo”) and changes the element content (innerHTML) to “Hello JavaScript”: document.getElementById(“demo”).innerHTML = “Hello JavaScript”; Try it Yourself » JavaScript accepts both double and single […]
JavaScript makes HTML pages more dynamic and interactive. Example My First JavaScript Click me to display Date and Time Try it Yourself » The HTML <script> Tag The <script> tag is used to define a client-side script (JavaScript). The <script> element either contains scripting statements, or it points to an external script file through the src attribute. Common uses for JavaScript […]
Styling HTML with CSS CSS stands for Cascading Style Sheets. CSS describes how HTML elements are to be displayed on screen, paper, or in other media. CSS saves a lot of work. It can control the layout of multiple web pages all at once. CSS can be added to HTML elements in 3 ways: Inline – by using the style attribute in […]
Don’t worry if these examples use tags you have not learned. You will learn about them in the next chapters. HTML Documents All HTML documents must start with a document type declaration: <!DOCTYPE html>. The HTML document itself begins with <html> and ends with </html>. The visible part of the HTML document is between <body> and </body>. Example <!DOCTYPE html> <html> <body> <h1>My […]
What is HTML? HTML is the standard markup language for creating Web pages. HTML stands for Hyper Text Markup Language HTML describes the structure of Web pages using markup HTML elements are the building blocks of HTML pages HTML elements are represented by tags HTML tags label pieces of content such as “heading”, “paragraph”, “table”, […]
