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Arithmetic Operators

JavaScript provides 6 different operators to perform basic arithmetic operations on numbers.

• +: The addition operator is used to find the sum of numbers.

  1 + 2; // => 3
  2.5 + 3.9; // => 6.5

• -: The subtraction operator is used to find the difference between two numbers

  19 - 2; // => 17
  7.4 - 1.2; // => 6.2

• *: The multiplication operator is used to find the product of two numbers

  7 * 5; // => 35
  9.2 * 6.3; // => 57.959999999999994

• /: The division operator is used to divide two numbers. Since JavaScript numbers are always floating-point numbers, there is no integer division.

  8 / 2; // => 4
  25 / 3; // => 8.333333333333334

• %: The remainder operator is used to find the remainder of a division performed.

  40 % 4; // => 0
  11 % 4; // => 3
  -11 % 4; // => -3

• **: The exponentiation operator is used to raise a number to a power. It is the equivalent of using Math.pow()

  4 ** 3; // => 64
  4 ** 1 / 2; // => 2

Order of Operations

When using multiple operators in a line, JavaScript follows an order of precedence as shown in this precedence table. To simplify it to our context, JavaScript uses the PEDMAS (Parentheses, Exponents, Division/Multiplication, Addition/Subtraction) rule we’ve learnt in elementary math classes.

const result = 3 ** 3 + 9 * 4 / (3 - 1);
// => 3 ** 3 + 9 * 4/2
// => 27 + 9 * 4/2
// => 27 + 18
// => 45

Shorthand Assignment Operators

Shorthand assignment operators are a shorter way of writing code conducting arithmetic operations on a variable, and assigning the new value to the same variable. For example, consider two variables x and y. Then, x += y is same as x = x + y. Often, this is used with a number instead of a variable y. The 5 other operations can also be conducted in a similar style.

let x = 5;
x += 25; // x is now 30

let y = 31;
y %= 3; // y is now 1

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Originally from Exercism javascript concepts