Assignment operators in JavaScript allow us to assign values to variables
The most common assignment operator is the = operator. This operator is used to assign the value on the right to the variable on the left.
In addition to the basic assignment operator (=), there are compound assignment operators that combine an arithmetic operation with the assignment, simplifying and optimizing the code.
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Basic assignment operator (=)
The most common assignment operator is the =, which is used to assign the value on the right side to the variable on the left side.
| Operator | Name | Description |
|---|---|---|
= | Assignment | Assigns a value to a variable |
Let’s see it with an example,
let a = 5; // Assigns the value 5 to variable aIt can also be used to update the value of an existing variable:
let a = 5; // Initial assignment
a = 10; // Value updateDo not confuse the assignment operator = with the equality comparator ==.
Compound assignment operators
In addition to the basic operator, JavaScript offers several compound assignment operators that combine arithmetic operations with the assignment. These operators allow for more compact code.
| Operator | Name | Description |
|---|---|---|
+= | Add and assign | Adds the value to the variable and assigns the result |
-= | Subtract and assign | Subtracts the value from the variable and assigns the result. |
*= | Multiply and assign | Multiplies the variable by a value and assigns the result |
/= | Divide and assign | Divides the variable by a value and assigns the result |
%= | Modulo and assign | Calculates the modulo of the variable by a value and assigns the result |
Add and assign (+=)
The += operator adds a value to a variable and assigns the result to that variable.
let a = 5;
a += 3; // a is now 8 (equivalent to a = a + 3)Subtract and assign (-=)
The -= operator subtracts a value from a variable and assigns the result to that variable.
let a = 10;
a -= 3; // a is now 7 (equivalent to a = a - 3)Multiply and assign (*=)
The *= operator multiplies a variable by a value and assigns the result to that variable.
let a = 4;
a *= 6; // a is now 24 (equivalent to a = a * 6)Divide and assign (/=)
The /= operator divides a variable by a value and assigns the result to that variable.
let a = 20;
a /= 4; // a is now 5 (equivalent to a = a / 4)Modulo and assign (%=)
The %= operator calculates the modulo of a variable by a value and assigns the result to that variable.
let a = 17;
a %= 5; // a is now 2 (equivalent to a = a % 5)Exponentiation and assign (**=)
The **= operator raises a variable to the power of a value and assigns the result to that variable.
let a = 2;
a **= 3; // a is now 8 (equivalent to a = a ** 3)Operator precedence
It is important to note that assignment operators have a lower precedence than most other operators in JavaScript. Therefore, expressions on the right side of assignment operators are evaluated first.
let a = 5;
let b = 10;
a += b * 2; // a is now 25 (b * 2 is evaluated first, then a += 20)