Operators

An operator is a special character or series of characters that perform a task in JavaScript.

This operator uses the equals sign (=) to assign a value to a variable.

let x = 42;

In the snippet above, a variable x is declared and the numeric value 42 is assigned to it.

These operators are used to perform arithmetic on numeric values:

• +: Adds to a value; can also be used to concatenate strings.
• -: Subtracts from a value.
• *: Multiplies by a value.
• /: Divides by a value.
• %: Modulo finds the remainder after dividing two values.
• **: Returns the exponentiation of the first value raised to the power of the second value (first introduced in ES2016).
• ++: Returns the value incremented by 1.
• --: Returns the value decremented by 1.

Example

let sum = 5 + 5;

let difference = 10 - 5;

let product = 5 * 10;

let quotient = 10 / 5;

let remainder = 10 % 5;

An assignment operator assigns a value to its left operand based on the value of its right operand:

• +=: Adds and assigns a new value to a variable.
• -=: Subtracts and assigns a new value to a variable.
• *=: Multiplies and assigns a new value to a variable.
• /=: Divides and assigns a new value to a variable.
• %=: Assigns the returned remainder (modulo) as a new value to a variable.
• **=: Assigns the left operand raised to the power of the right operand.

Example

The following example showcases how these operators are a combination of using an assignment and arithmetic operator in one statement:

let number = 100;

// Both statements will add 10
number = number + 10;
number += 10;

console.log(number);
// Output: 120

These operators compare values and return a boolean value of true or false.

• ==: Returns true or false based on whether the value of two operands are equal.
• ===: Returns true or false based on whether the value and type of two operands are equal.
• !=: Returns true or false based on whether the value of two operands are not equal.
• !==: Returns true or false based on whether the value and type of two operands are not equal.
• >: Returns true or false based on whether the first value is greater than the second value.
• <: Returns true or false based on whether the first value is less than the second value.
• >=: Returns true or false based on whether the first value is greater than or equal to the second value.
• <=: Returns true or false based on whether the first value is less than or equal to the second value.

Note: The == and === comparison operators are not to be confused with the single equality sign = operator that is used for assignment.

Example

The following example showcases some of these comparison operators:

let tenString = '10';
let numberTen = 10;

console.log(tenString == numberTen);
// Output: true

console.log(tenString === numberTen);
// Output: false

console.log(tenString != numberTen);
// Output: false

console.log(tenString !== numberTen);
// Output: true

These operators combine multiple boolean expressions or values to provide a single boolean output:

• && (AND): Returns true if all operands evaluate to true.
• || (OR): Returns true if one or more operands evaluate to true.
• ! (NOT): Returns the logical opposite of an operand’s boolean value (i.e., !(true) returns false and !(false) returns true).

Example

The following example showcases the usage of logical operators:

const walksLikeADuck = true;
const talksLikeADuck = true;

// AND Operator
let isDuck = walksLikeADuck && talksLikeADuck;

console.log(isDuck);
// Output: true

const isBird = true;
const isPlane = false;

// OR Operator
isDuck = isBird || isPlane;

console.log(isDuck);
// Output: true

// NOT Operator
const isPenguin = !isDuck;

console.log(isPenguin);
// Output: false

The conditional, or ternary, operator uses the question mark ? and colon : characters to assign a value to a variable based on a conditional statement:

variable = condition ? assignedIfTrue : assignedIfFalse;

This operator combines the functionalities of the assignment, comparison, and logical operators.

Codebyte Example

The following example showcases the conditional operator:

Code
Output
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