Flash cards
Review the key moves
What is the main idea behind JavaScript Operators?
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.
Operators are for Mathematical and Logical Computations
The Assignment Operator = assigns values
The Addition Operator + adds values
The Multiplication Operator * multiplies values
The Comparison Operator > compares values
JavaScript Assignment
The Assignment Operator ( = ) assigns a value to a variable:
Assignment Examples
let x = 10;JavaScript Addition
The Addition Operator ( + ) adds numbers:
Adding
let x = 5;
let y = 2;
let z = x + y;JavaScript Multiplication
The Multiplication Operator ( * ) multiplies numbers:
Multiplying
let x = 5;
let y = 2;
let z = x * y;Types of JavaScript Operators
There are different types of JavaScript operators:
- Arithmetic Operators
- Assignment Operators
- Comparison Operators
- Logical Operators
- And more ...
JavaScript Arithmetic Operators
Arithmetic Operators are used to perform arithmetic on numbers:
Arithmetic Operators Example
let a = 3;
let x = (100 + 50) * a;| Operator | Description |
|---|---|
| + | Addition |
| - | Subtraction |
| * | Multiplication |
| ** | Exponentiation |
| / | Division |
| % | Modulus (Division Remainder) |
| ++ | Increment |
| -- | Decrement |
Arithmetic operators are fully described in the JS Arithmetic chapter.
JavaScript String Addition
The + can also be used to add (concatenate) strings:
Example
let text1 = "John";
let text2 = "Doe";
let text3 = text1 + " " + text2;The += assignment operator can also be used to add (concatenate) strings:
Example
let text1 = "What a very ";
text1 += "nice day";When used on strings, the + operator is called the concatenation operator.
Adding Strings and Numbers
Adding two numbers, will return the sum as a number like 5 + 5 = 10.
Adding a number and a string, will return the sum as a concatenated string like 5 + "5" = "55".
Example
let x = 5 + 5;
let y = "5" + 5;
let z = "Hello" + 5;If you add a number and a string, the result will be a string!
JavaScript Assignment Operators
Assignment operators assign values to JavaScript variables.
The Addition Assignment Operator ( += ) adds a value to a variable.
Assignment
let x = 10;
x += 5;| Operator | Example | Same As |
|---|---|---|
| = | x = y | x = y |
| += | x += y | x = x + y |
| -= | x -= y | x = x - y |
| *= | x *= y | x = x * y |
| /= | x /= y | x = x / y |
| %= | x %= y | x = x % y |
| **= | x **= y | x = x ** y |
Assignment operators are fully described in the JS Assignment chapter.
JavaScript Comparison Operators
Comparison operators are used to compare two values .
Comparison operators always return true or false .
Example
let x = 5;
let result = x > 8;| Operator | Description | Example |
|---|---|---|
| == | equal to | x == 5 |
| === | equal value and equal type | x === 5 |
| != | not equal | x != 5 |
| !== | not equal value or not equal type | x !== 5 |
| > | greater than | x > 5 |
| < | less than | x < 5 |
| >= | greater than or equal to | x >= 5 |
| <= | less than or equal to | x <= 5 |
All the comparison operators above can also be used on strings:
Example
let text1 = "A";
let text2 = "B";
let result = text1 < text2;Note that strings are compared alphabetically.
Comparison operators are fully described in the JS Comparisons chapter.
JavaScript Logical Operators
| Operator | Description |
|---|---|
| && | logical and |
| logical or | |
| ! | logical not |
Logical operators are fully described in the JS Logical chapter.