JavaScript Math functions examples

List of usefull JavaSript functions and constans

var 1_radian_to_degree = 180 / Math.PI; // 57,295779513082320876798154814105 degree
var 1_degree_to_radian = Math.PI / 180; // 0,01745329251994329576923690768489 radian
var 360_degree =  2 * Math.PI * 1_radian_to_degree;

parseInt("10.33") // returns 10 string to integer
parseFloat("10.33") // returns 10.33 string to float

// change sign
var a = -1;
a = a * -1; // +1
// random sign
a *= Math.floor(Math.random()*2) == 1 ? 1 : -1; 

var who_is = 58;
var type = (typeof who_is); // number

Math.E  // natural logarithms, e, approximately 2.718281828459045
Math.LN10 // natural logarithm of 10, approximately 2.302585092994046
Math.LN2 // natural logarithm of 2, approximately 0.6931471805599453
Math.PI // approximately 3.141592653589793
Math.SQRT1_2 // square root of 1/2 which is approximately 0.7071067811865476
Math.SQRT2 // square root of 2, approximately 1.4142135623730951
Math.pow(4, 2) = 16 // 4 x 4 ... base 4 to the exponent 2 power
Math.abs(-5) absolute value of a number // return 5

Math.tan(degrees * Math.PI / 180) // get tangent from degrees
Math.tan(degree * Math.PI / 180)*adjacent = opposite
opposite / Math.tan(degree * Math.PI / 180) = adjacent
Math.acos(adjacent / hypotenuse) // angle of a right-angle triangle in radians
Math.atan(opposite / adjacent) // angle of a right-angle triangle in radians
var adjacent = Math.cos(radian) * hypotenuse; // leng of adjacent side 
// find the point on a circle if you know the circle´s radius
var x = Math.cos(pointAngleInRadiansFromCentreOfCircle) * radius;
var y = Math.sin(pointAngleInRadiansFromCentreOfCircle) * radius;

Math.cbrt(64) //  cube root of a number 4 (4 x 4 x 4)
Math.exp(xNumber) // returns e<sup>xNumber</sup> ... e == Math.E 

Math.ceil() // always rounds a number up to the next largest integer
Math.ceil(1.001) // 2

Math.floor() // returns largest integer less than or equal to a given number
Math.floor(5.85) = 5
Math.floor(-5.15) = -6

const arrayA = [2, 3, 1];
Math.min(...arrayA) = 1;
Math.max(1, 3, 2) = 3;

Math.random() // returns 0.000.... - 0.99999999999
Math.random() * 3 // returns 0.000 - 2.99999999999

Math.round() // returns value of a number rounded to the nearest integer.
Math.round(0.9) // 1
Math.round(5.5) // 6
Math.round(5.05) // 5 

Math.floor(Math.random() * 3) // returns 0, 1, 2