Flash cards
Review the key moves
What is the main idea behind JavaScript Assignment?
Lesson checks
Practice each idea before moving on
Short Mimo-style checks built from this lesson's code, terms, and sequence.
Which statement best captures the main point of this lesson?
Put the learning moves in the order that makes the concept easiest to apply.
JavaScript Assignment Operators
Assignment operators assign values to JavaScript variables.
Given that x = 10 and y = 5 , the table below explains the assignment operators:
| Operator | Example | Same As | Result |
|---|---|---|---|
| = | x = y | x = y | x = 5 |
| += | x += y | x = x + y | x = 15 |
| -= | x -= y | x = x - y | x = 5 |
| *= | x *= y | x = x * y | x = 50 |
| **= | x **= y | x = x ** y | x = 100000 |
| /= | x /= y | x = x / y | x = 2 |
| %= | x %= y | x = x % y | x = 0 |
| : | x: 45 | size.x = 45 | x = 45 |
Logical Assignment Operators
| Operator | Example | Result | |
|---|---|---|---|
| &&= | true &&= 10 | x = 10 | |
| = | false | = 10 | x = 10 |
| ??= | null ??= 10 | x = 10 |
The = Operator
The Simple Assignment Operator assigns a simple value to a variable.
Simple Assignment Examples
let x = 10;The += Operator
The Addition Assignment Operator adds a value to a variable.
Addition Assignment Examples
let x = 10;
x += 5;The -= Operator
The Subtraction Assignment Operator subtracts a value from a variable.
Subtraction Assignment Example
let x = 10;
x -= 5;The *= Operator
The Multiplication Assignment Operator multiplies a variable.
Multiplication Assignment Example
let x = 10;
x *= 5;The **= Operator
The Exponentiation Assignment Operator raises a variable to the power of the operand.
Exponentiation Assignment Example
let x = 10;
x **= 5;The /= Operator
The Division Assignment Operator divides a variable.
Division Assignment Example
let x = 10;
x /= 5;The %= Operator
The Remainder Assignment Operator assigns a remainder to a variable.
Remainder Assignment Example
let x = 10;
x %= 5;String Assignment
Two assignment operators can assign values to strings:
The Simple Assignment Operator assigns a simple value to a string.
The Addition Assignment Operator adds a value to a string.
The = Operator
String Assignment
let text = "Hello";The += Operator
The Addition Assignment Operator Can also be used to add strings.
Addition Assignment Example
let text = "Hello";
text += " World";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 Examples
let x = true;
let y = x &&= 10;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 Examples
let x = false;
let y = x ||= 10;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 Examples
let x;
x ??= 10;The ??= operator is an ES2020 feature .
The 8 FALSY Values
| false | The boolean keyword itself |
|---|---|
| 0 | The number zero |
| -0 | Negative zero |
| 0n | BigInt zero |
| "", '', `` | Any empty string |
| null | The absence of any value |
| undefined | A variable that has not been assigned a value |
| NaN | "Not-a-Number," usually the result of an invalid math operation |
These are TRUTHY
It is a common mistake to think these are falsy, but they actually evaluate to true:
| "0" | A string containing a zero is truthy because it is not empty |
|---|---|
| "false" | The string "false" is truthy |
| [ ] | An empty array is truthy |
| { } | An empty object is truthy |
The Spread (...) Operator
The ... operator splits iterables into individual elements.
Example
let text = "12345";
let min = Math.min(...text);
let max = Math.max(...text);