JavaScript Operators

Arithmetic Operators

Arithmetic operators are symbols used in programming and mathematics to perform basic mathematical operations. Here are the common ones:

• Addition (+): Adds two values. For example, 5 + 3 equals 8.
• Subtraction (-): Subtracts one value from another. For example, 5 - 3 equals 2.
• Multiplication (*): Multiplies two values. For example, 5 * 3 equals 15.
• Division (/): Divides one value by another. For example, 6 / 3 equals 2.
• Modulus (%): Gives the remainder of a division operation. For example, 5 % 3 equals 2.

Assignment Operators

An assignment operator assigns a value to its left operand based on the value of its right operand. Here are some of them:

• += addition assignment
• -= subtraction assignment
• *= multiplication assignment
• /= division assignment

let number = 100;
 
// Both statements will add 10
number = number + 10;
number += 10;
 
console.log(number);
// 120

What is the difference between and = ?

The  equality operator converts the operands if they are not of the same type, then applies strict comparison. The = strict equality operator only considers values equal that have the same type.

console.log(1 == '1'); // true
console.log(1 === '1'); // false
console.log(1 === 1); // true

Logical Operators

||

The logical OR operator || checks two values and returns a boolean. If one or both values are truthy, it returns true. If both values are falsy, it returns false.

B	A	A || B
false	false	false
true	false	true
false	true	true
true	true	true

&&

The logical AND operator && checks two values and returns a boolean. If both values are truthy, then it returns true. If one, or both, of the values is falsy, then it returns false.

true && true;      // true
1 > 2 && 2 > 1;    // false
true && false;     // false
4 === 4 && 3 > 1;  // true

!

Ternary operator

The ternary operator allows for a compact syntax in the case of binary (choosing between two choices) decisions.

variable = bedingung ? wertWennWahr : wertWennFalsch;

Example

let price = 10.5;
let day = "Monday";
 
day === "Monday" ? price -= 1.5 : price += 1.5;