JavaScript Variables are named memory locations that hold a value. JavaScript supports only a handful of data types. The primitive types are number, string, boolean, and two special types: null and undefined. Primitive Types Primitive types are the basic, ready-to-use variable types that are ...
Lesson 1: What is JavaScript? Explore the quirky history of the JavaScript language,Learn how to use the JavaScript console and write your first line of JavaScript code Lesson 2: Data Types & Variables Use a variety of data types to represent data in your code,Learn how to store data using...
包含第一种方法代码的文件路径是:github.com/TrainingByPackt/Professional-JavaScript/blob/master/Lesson01/Exercise05/first_approach.js。 包含第二种方法代码的文件路径是:github.com/TrainingByPackt/Professional-JavaScript/blob/master/Lesson01/Exercise05/second_approach.js。 在这个练习中,我们使用了两种不同的...
Now we create a length variable with a value14but this time using thelet keyword. When we redeclare the same variable with another value we get aSyntaxErrorsaying it has already been declared. The first point of difference betweenlet and varis that usingvarwe can redeclare those variables but ...
Overview and History of JavaScript, jQuery, TypeScript Setting Up jQuery in Your Projects Add and Remove Elements DOM Manipulation Animations and Effects jQuery Plugins and UI Components JavaScript Syntax and Structure Variables, Data Types, and Operators Control Flow: Conditionals and Loops Arrays and...
Lesson Summary Hands-on LAB Activities 1 Introduction to JavaScript Understanding Basic Concepts of JavaScript (JS) 2 Working with Variables and Data in JavaScript Working with data types Using arithmetic operators - Part 1 Using arithmetic operators - Part 2 Using comparison and logical operat...
In a programming language, variables are used to store data values. JavaScript uses the var keyword to declare variables. An equal sign is used to assign values to variables. In this example, x is defined as a variable. Then, x is assigned (given) the value 6: var x; x = 6; docume...
We will use those to size up the canvas to be the width and height values that we set in the variables.const WIDTH = 1500; const HEIGHT = 1500; const canvas = document.querySelector('canvas'); const ctx = canvas.getContext('2d'); canvas.width = WIDTH; canvas.height = HEIGHT;...
In the table below the variables are: a = 1 and b = 2. OperatorOperationExpressionResult == Equal to a == b false != Not equal to a != b true <= Less than equal to a <= b true >= Greater than or equal to a >= b false < Less than a < b true > Greater than a > ...
Using the Array Object var newsSections = new Array(6); JavaScript represents arrays with the Array object Contains a special constructor named Array() Constructor Special function type used as the basis for creating reference variables Syntax var newsSections = new Array(6); Array literals preferr...