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Assignment operators assign values to JavaScript variables.
Shift Assignment Operators
Bitwise assignment operators, logical assignment operators, the = operator.
The Simple Assignment Operator assigns a value to a variable.
Simple Assignment Examples
The += operator.
The Addition Assignment Operator adds a value to a variable.
Addition Assignment Examples
The -= operator.
The Subtraction Assignment Operator subtracts a value from a variable.
Subtraction Assignment Example
The *= operator.
The Multiplication Assignment Operator multiplies a variable.
Multiplication Assignment Example
The **= operator.
The Exponentiation Assignment Operator raises a variable to the power of the operand.
Exponentiation Assignment Example
The /= operator.
The Division Assignment Operator divides a variable.
Division Assignment Example
The %= operator.
The Remainder Assignment Operator assigns a remainder to a variable.
Remainder Assignment Example
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The <<= Operator
The Left Shift Assignment Operator left shifts a variable.
Left Shift Assignment Example
The >>= operator.
The Right Shift Assignment Operator right shifts a variable (signed).
Right Shift Assignment Example
The >>>= operator.
The Unsigned Right Shift Assignment Operator right shifts a variable (unsigned).
Unsigned Right Shift Assignment Example
The &= operator.
The Bitwise AND Assignment Operator does a bitwise AND operation on two operands and assigns the result to the the variable.
Bitwise AND Assignment Example
The |= operator.
The Bitwise OR Assignment Operator does a bitwise OR operation on two operands and assigns the result to the variable.
Bitwise OR Assignment Example
The ^= operator.
The Bitwise XOR Assignment Operator does a bitwise XOR operation on two operands and assigns the result to the variable.
Bitwise XOR Assignment Example
The &&= operator.
The Logical AND assignment operator is used between two values.
If the first value is true, the second value is assigned.
Logical AND Assignment Example
The &&= operator is an ES2020 feature .
The ||= Operator
The Logical OR assignment operator is used between two values.
If the first value is false, the second value is assigned.
Logical OR Assignment Example
The ||= operator is an ES2020 feature .
The ??= Operator
The Nullish coalescing assignment operator is used between two values.
If the first value is undefined or null, the second value is assigned.
Nullish Coalescing Assignment Example
The ??= operator is an ES2020 feature .
Test Yourself With Exercises
Use the correct assignment operator that will result in x being 15 (same as x = x + y ).
Start the Exercise
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JavaScript Variables
Variables are used to store data in JavaScript so that we can later access the data. JavaScript is a dynamically typed language so the type of variables is decided at runtime. Therefore there is no need to explicitly define the type of a variable. We can declare variables in JavaScript in three ways:
- JavaScript var keyword
- JavaScript let keyword
- JavaScript const keyword
Interesting Facts about Variables in JavaScript
1. let or const are preferred over var: Initially, all the variables in JavaScript were written using the var keyword but in ES6 the keywords let and const were introduced. The main issue with var is, scoping.
2. var is function scoped: Can be accessed outside block if within the function .
3. let and const are block scoped : Cannot be accessed outside block even if inside the same function
4. var can be redeclared in the same scope, but let and const cannot be
5. We can change elements of array or objects even if declared as const.
Examples of var, let and const
Example of var
Example of let
Example of const
When to Use var, let, or const
- We declare variables using const if the value should not be changed
- We should use let if we want mutable value or we can not use const
- We use var only if we support old browser.
To learn more about the scope of variables refer to this article Understanding variable scopes in JavaScript
Comparison of properties of let, var, and const keywords in JavaScript:
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