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Learn how to declare and assign variables using var in JavaScript. See examples, syntax, parameters, and browser support for var.
- Overview
- Syntax
- Description
- Examples
- Browser compatibility
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The var statement declares function-scoped or globally-scoped variables, optionally initializing each to a value.
nameN
The name of the variable to declare. Each must be a legal JavaScript identifier or a destructuring binding pattern.
valueN Optional
Initial value of the variable. It can be any legal expression. Default value is undefined.
The scope of a variable declared with var is one of the following curly-brace-enclosed syntaxes that most closely contains the var statement:
•Function body
•Static initialization block
Or if none of the above applies:
•The current module, for code running in module mode
•The global scope, for code running in script mode.
Declaring and initializing two variables Assigning two variables with single string value
This is equivalent to: Be mindful of the order: Here, x and y are declared before any code is executed, but the assignments occur later. At the time x = y is evaluated, y exists so no ReferenceError is thrown and its value is undefined. So, x is assigned the undefined value. Then, y is assigned the value "A".
Initialization of several variables
Be careful of the var x = y = 1 syntax — y is not actually declared as a variable, so y = 1 is an unqualified identifier assignment, which creates a global variable in non-strict mode. The same example as above but with a strict mode:
Implicit globals and outer function scope
Variables that appear to be implicit globals may be references to variables in an outer function scope:
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Learn how to use the var statement to declare and initialize variables in JavaScript, and how their scope and hoisting work. See examples, syntax, and differences with let and const.
Learn how to declare and use variables in JavaScript with var, let, and const keywords. See examples of different data types, identifiers, assignment, and arithmetic operations.
Jul 26, 2024 · Learn how to declare variables with function scope or globally using var in JavaScript. See examples, syntax, hoisting, redeclaration, and deletion of var variables.
May 12, 2024 · We can declare variables in JavaScript in three ways: JavaScript var keyword. JavaScript let keyword. JavaScript const keyword. Note: In JavaScript, variables can be declared automatically. Syntax. // Declaration using varvar geek = "Hello Geek"// Declaration using let let $ = "Welcome" // Declaration using const const _example = "Gfg"
- 6 min
Jul 25, 2024 · Learn how to declare, initialize, and use variables in JavaScript, the dynamic client-side scripting language. Variables are containers for values that can store any data type, such as strings, numbers, or functions.
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Learn how to declare, initialize, and use variables in JavaScript with var, let, and const keywords. Find out the difference between global and local variables, dynamic typing, and constant variables.
