See short-circuit evaluation for the explanation. It's a common way of implementing these operators; it is not unique to JavaScript.
Answer from unwind on Stack OverflowDigitalOcean
digitalocean.com › community › tutorials › understanding-variables-scope-hoisting-in-javascript
Understanding Variables, Scope, and Hoisting in JavaScript | DigitalOcean
August 24, 2021 - This tutorial will cover what variables ... hoisting and the significance of global and local scope to a variable’s behavior. A variable is a named container used for storing values....
Turing
frontend.turing.edu › lessons › module-1 › js-intro-to-data-types-variables.html
JS: Data Types & Variables - Front-End Engineering Curriculum - Turing School of Software and Design
Primitive type A kind of data type. Primitives in Javascript are [string, number, boolean, null, undefined, symbol]. Also know as a simple data type · Variable A container for a value.
JavaScript OR (||) variable assignment explanation - Stack Overflow
Given this snippet of JavaScript... var a; var b = null; var c = undefined; var d = 4; var e = 'five'; var f = a || b || c || d || e; alert(f); // 4 · Can someone please explain to me what this technique is called (my best guess is in the title of this question!)? And how/why it works exactly? My understanding is that variable ... More on stackoverflow.com
What is the purpose of the global object in JavaScript?
Pretty much everything is stored in the window object. It's easier to think of the window object as the root object. Whenever you define anything it is either a part of the window object or it is part of another object who has a parent somewhere that is in the window object. More on reddit.com
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July 18, 2018Why is everything considered a variable in javascript?
JavaScript has first-class-functions (*1), thats why you can assign functions to variables. JavaScript has no classes like Java does. JavaScript uses prototype inheritance (*2) and has only 'objects'. To work with objects you must assign them to variables, just like you do in Java, right?
And don't let ES6 confuse you. Even ES6 does not have real classes. The class syntax in ES6 is just syntactic sugar on top of the <=ES5 prototype system ..
The good thing is you have only three things in JavaScript: Everything is either a function (and some folks may also argue that a function in JS is a special object), an object or a primitive. And there are only a few primitives as well .. makes the language pretty simple. But sometimes simpler is better ;)
*1: https://en.wikipedia.org/wiki/First-class_function
More on reddit.com*2: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Inheritance_and_the_prototype_chain
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December 16, 2015JS: Assigning values to multiple variables
Nothing wrong with let a = 5; let b = 8; let c = 12; More on reddit.com
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March 29, 2021Videos
03:51
Introduction to JavaScript Variables - YouTube
14:57
JavaScript Variables | JS for Beginners #javascript #js - YouTube
11:36
Variables & Comments in JavaScript (With Examples) – Part 1 - ...
12:49
JavaScript VARIABLES are easy! 📦 - YouTube
JavaScript Variables and Scope | JavaScript Tutorial for ...
12:21
The Secrets of JavaScript Variables - YouTube
Codecademy
codecademy.com › docs › javascript › variables
JavaScript | Variables | Codecademy
October 5, 2024 - Variables are used to store a piece of data at a named location in memory.
W3Schools
w3schools.com › js › js_variables.asp
JavaScript Variables
The variable total is declared with the let keyword. The value of total can be changed. Undeclared variables are automatically declared when first used: ... It's a good programming practice to declare all variables at the beginning of a script. The var keyword was used in all JavaScript code before 2015.
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See short-circuit evaluation for the explanation. It's a common way of implementing these operators; it is not unique to JavaScript.
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This is made to assign a default value, in this case the value of y, if the x variable is falsy.
The boolean operators in JavaScript can return an operand, and not always a boolean result as in other languages.
The Logical OR operator (||) returns the value of its second operand, if the first one is falsy, otherwise the value of the first operand is returned.
For example:
"foo" || "bar"; // returns "foo"
false || "bar"; // returns "bar"
Falsy values are those who coerce to false when used in boolean context, and they are 0, null, undefined, an empty string, NaN and of course false.
GeeksforGeeks
geeksforgeeks.org › javascript › variables-datatypes-javascript
Variables and Datatypes in JavaScript - GeeksforGeeks
Non-Primitive Data Types: Includes Object, Array, and Function used to store complex data. A variable is like a container that holds data that can be reused or updated later in the program.
Published 3 days ago
GeeksforGeeks
geeksforgeeks.org › javascript › javascript-variables
JavaScript Variables - GeeksforGeeks
Variables in JavaScript are used to store data values. They can be declared in different ways depending on how the value should behave. Variables can be declared using var, let, or const.
Published January 19, 2026
GeeksforGeeks
geeksforgeeks.org › javascript › javascript-operators
JavaScript Operators - GeeksforGeeks
JavaScript operators are symbols or keywords used to perform operations on values and variables. They are the building blocks of JavaScript expressions and can manipulate data in various ways.
Published 3 days ago
MDN Web Docs
developer.mozilla.org › en-US › docs › Web › JavaScript › Reference › Statements › var
var - JavaScript | MDN
The name of the variable to declare. Each must be a legal JavaScript identifier or a destructuring binding pattern. ... Initial value of the variable. It can be any legal expression. Default value is undefined.
Mindsers Blog
mindsers.blog › en › post › learn-javascript-variables
Start Javascript: learn about variables - Mindsers Blog
October 3, 2022 - Which means that abc could have the value 5 if you run the software again or even during the same run of it. This is where the name "variable" comes from. It is a bit of code that can vary depending on several factors. In JavaScript, the definition of a variable (which is when you create a ...
JavaScript.info
javascript.info › tutorial › the javascript language › javascript fundamentals
Variables
3 weeks ago - Here are two examples: An online ... and much more. Variables are used to store this information. A variable is a “named storage” for data....
TutorialsTeacher
tutorialsteacher.com › javascript › javascript-variable
JavaScript Variables (With Examples)
In JavaScript, a variable can be declared using var, let, const keywords. var keyword is used to declare variables since JavaScript was created.
SheCodes
shecodes.io › athena › 80418-what-is-var-in-javascript-and-how-to-declare-variables-using-it
[JavaScript] - What is var in JavaScript and how to declare variables using it
`var` is a keyword used in JavaScript to declare a variable. Learn how to declare variables using `var` and see an example.
CodeSweetly
codesweetly.com › javascript-variable
Variable in JavaScript – Explained with Examples | CodeSweetly
A JavaScript variable is a container used to store JavaScript data (values). ... JavaScript variables differ from mathematical or other generic variables. JavaScript variables are so powerful that you can use them to store various kinds of values ...
Mozilla
developer.mozilla.org › en-US › docs › Web › JavaScript › Guide › Grammar_and_types
Grammar and types - JavaScript | MDN
This is called hashbang comment syntax, and is a special comment used to specify the path to a particular JavaScript engine that should execute the script. See Hashbang comments for more details. JavaScript has three kinds of variable declarations. ... Declares a variable, optionally initializing it to a value.
CodeHS
codehs.com › tutorial › rachel › variables-in-javascript
Tutorial: Variables in JavaScript | CodeHS
Learn the basics of variables in JavaScript.
freeCodeCamp
freecodecamp.org › news › how-to-declare-variables-in-javascript
How to Declare Variables in JavaScript – var, let, and const Explained
November 7, 2023 - Let's dive into these different ways of declaring variables in JavaScript so you know how they work and when to use each one. When you declare variables in your app, the interpreter moves them to the top of their scope and allocates places in the memory before the execution starts. This process is called Hoisting.
Basponccollege
basponccollege.org › LMS › EMaterial › Science › Comp › HVP › JS Notes.pdf pdf
JAVASCRIPT Notes By – Prof Harshal V Patil Page 1 JAVASCRIPT
Java and JavaScript are two completely ... and - depending on the browser - load another page specifically designed for that ... Variables are "containers" for storing information....
javascript.com
javascript.com › learn › variables
Learn to use JavaScript variables with this free resource
Variables are named values and can store any type of JavaScript value.
Code Institute
codeinstitute.net › blog › javascript › javascript variables
Javascript Variables : A Guide - Code Institute DE
April 24, 2023 - An object (or designated memory space) called a JavaScript variable is used to hold a value that can be used throughout program execution. Just as in other programming languages, a variable in JavaScript has a title, a value, and a memory address.