Javascript Arithmetic Cheat Sheet
Given that one of the main reason computers were invented was to solve mathematical problems quickly, it is no wonder that all the modern programming languages are so rich in arithmetic-oriented methods. The earliest computers were basically just calculators. (Yes, I'm looking at you Abacus). If you dabble in Javascript (and a little math every now and then), you might find this useful. The very obvious operations like simple addition (+) and subtraction (-) have been omitted. So have more advanced operations.
Working with constants
Logarithm to base e
Math.E; // 2.718281828459045
Logarithm to base 10
Math.LN10; // 2.302585092994046
Logarithm to base 2
Math.LN2; // 0.6931471805599453
Base 10 logarithm of e
Math.LOG10E; // 0.4342944819032518
Base 2 logarithm of e
Math.LOG2E; // 1.4426950408889634
🥧
Math.PI; // 3.141592653589793
Square root of 1/2
Math.SQRT1_2; // 0.7071067811865476
Square root of 2
Math.SQRT2; // 1.4142135623730951
Infinity
Infinity; // Infinity
Rounding
Math.round returns the value of a number rounded to the
nearest integer.
Math.round(4.2); // 4
Math.round(4.7); // 5
Math.round(4.5); // 5. Half-way values are always rounded up
Speaking of rounding up, Math.ceil():
Math.ceil(4.2); // 5
Math.ceil(4.7); // 5
Math.ceil(-4.7); // -4. Ceiling a negative number will round towards zero
Math.floor() rounds down:
Math.floor(4.2); // 4
Math.floor(4.7); // 4
Math.floor(-4.7); // -5. Flooring a negative number will round away from zero
Modulus (%)
Returns the remainder after (integer) division.
42 % 10; // 2
-40 % 10; // -0 🤔
Trigonometry
Sine
Math.sin(60); // -0.3048106211022167
Cosine
Math.cos(60); // -0.9524129804151563
Tangent
Math.tan(60); // 0.320040389379563
Incrementing (++)
++ increments its operand by 1.
// postfix: returns the value before incrementing
let a = 4, // 4
b = a++, // 4
c = a; //5
// prefix: returns the value after incrementing
let a = 4, // 4
b = ++a, // 5
c = a; //5
Decrementing (–)
-- decrements its operand by 1.
// postfix: returns the value before decrementing
let a = 4, // 4
b = a--, // 4
c = a; //3
// prefix: returns the value after decrementing
let a = 4, // 4
b = -a, // 3
c = a; //3
Exponentiation (**)
// Math.pow() or ** can be used
let a = 4,
b = 2,
c = Math.pow(a, b), // 16
d = a ** b; // 16
Getting maximum and minimum
Math.max(4.2, 4.7); // 4.7
Math.min(4.2, 4.7); // 4.2
Getting maximum and minimum from an array:
const arr = [1, 2, 3, 4, 5, 6, 7, 8, 9],
max = Math.max(...arr), // 9
min = Math.min(...arr); // 1
Getting roots √
Square Root
Math.sqrt(16); // 4
Cube Root
Math.cbrt(27); // 3
To find the nth-root, use the Math.pow() function and pass in a fractional exponent.
// This finds the 6th root of 64
Math.pow(64, 1 / 6); // 4
Much more complex calculations can be done by combining one or more of these operations.