Assignment Operators: Storing and Updating Values
In JavaScript, assignment operators are used to assign values to variables. The most basic one is the simple assignment operator (=), but there are also several compound assignment operators that provide a shorthand for performing an operation and assigning the result back to the variable.
1. Simple Assignment (=)
The equal sign (=) is the most fundamental assignment operator. It assigns the value of the right-hand operand to the variable specified by the left-hand operand.
Examples:
2. Compound Assignment Operators
These operators combine an arithmetic (or other) operation with assignment. They provide a concise way to update a variable's value based on its current value.
| Operator | Example | Equivalent To | Description |
|---|---|---|---|
+= | x += y | x = x + y | Adds y to x, then assigns the result to x. |
-= | x -= y | x = x - y | Subtracts y from x, then assigns the result to x. |
*= | x *= y | x = x * y | Multiplies x by y, then assigns the result to x. |
/= | x /= y | x = x / y | Divides x by y, then assigns the result to x. |
%= | x %= y | x = x % y | Assigns the remainder of x / y to x. |
**= | x **= y | x = x ** y | Raises x to the power of y, then assigns the result to x. |
Examples of Compound Assignment Operators:
Addition Assignment (+=)
Subtraction Assignment (-=)
Multiplication Assignment (*=)
Division Assignment (/=)
Modulo Assignment (%=)
Exponentiation Assignment (**=)
Why use Compound Assignment Operators?
- Conciseness: They make your code shorter and often easier to read by reducing repetition.
- Readability: For simple operations,
x += 5is often clearer and faster to parse thanx = x + 5. - Efficiency: While modern JavaScript engines are highly optimized, these operators can sometimes represent a more direct instruction, potentially leading to minor performance benefits in complex scenarios.
It's a good practice to use compound assignment operators whenever you're updating a variable based on its own value.
Exercise: Applying Assignment Operators
In the editor below, perform the following tasks and log each variable's final value to the console. Follow the comments to complete the exercise!