Operators

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

Assignment Operator

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.

Arithmetic Operators

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;

Other Assignment Operators

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

Comparison Operators

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

Logical Operators

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

Conditional Operator

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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