Talk about Math_javascript skills of JavaScript type system

A must read when opening the door

Math is different from other objects. The Math object is a static object, not a constructor. In fact, Math is just an object namespace set by Javascript to store mathematical functions

Attributes

Math.E is the base of the natural logarithm, which is the value of the constant e (approximately equal to 2.718)
Math.PI pie value (approximately equal to 3.14159)
console.log(Math.E);//2.718281828459045
console.log(Math.PI);//3.141592653589793
Math.LN2 Natural logarithm of 2 (approximately equal to 0.693)
Math.LN10 The natural logarithm of 10 (approximately equal to 2.302)
Math.LOG2E The logarithm of e with base 2 (approximately equal to 1.414)
Math.LOG10E The logarithm of e with base 10 (approximately equal to 0.434)
console.log(Math.LN2);//0.6931471805599453
console.log(Math.LN10);//2.302585092994046
console.log(Math.LOG2E);//1.4426950408889634
console.log(Math.LOG10E);//0.4342944819032518
Math.SQRT2 The square root of 2 (approximately equal to 1.414)
Math.SQRT1_2 The square root of 1/2, which is the reciprocal of the square root of 2 (approximately equal to 0.707)
console.log(Math.SQRT2);//1.4142135623730951
console.log(Math.SQRT1_2);//0.7071067811865476

Method

These methods all involve Number() implicit type conversion; if it exceeds the scope of the method, NaN will be returned

Math.min() returns the minimum value in a set of numbers
Math.max() returns the maximum value in a set of numbers
console.log(Math.min(1,2,3));//1
console.log(Math.max(1,2,3));//3
Math.ceil(num) rounds up to an integer
Math.floor(num) rounds down to an integer
Math.round(num) rounds to an integer
console.log(Math.ceil(12.6));//13
console.log(Math.floor(12.6));//12
console.log(Math.round(12.6));//13
Math.abs(num) returns the absolute value of num
Math.random() returns a random number greater than or equal to 0 and less than 1
console.log(Math.abs(-10));//10
console.log(Math.random());//0.741887615993619
Math.exp(num) returns the num power of Math.E
Math.log(num) returns the natural logarithm of num
Math.sqrt(num) returns the square root of num (x must be a number greater than or equal to 0)
Math.pow(num,power) returns num raised to the power
console.log(Math.exp(0));//1
console.log(Math.log(10));//2.302585092994046
console.log(Math.sqrt(100));//10
console.log(Math.pow(10,2));//100
Math.sin(x) returns the sine value of x
Math.cos(x) returns the cosine of x
Math.tan(x) returns the tangent of x
Math.asin(x) returns the arcsine of x (x must be a number between -1 and 1)
Math.acos(x) returns the inverse cosine of x (x must be a number between -1 and 1)
Math.atan(x) returns the arctangent of x
Math.atan2(y,x) returns the arctangent of y/x
console.log(Math.sin(30*Math.PI/180));//0.49999999999999994
console.log(Math.cos(60*Math.PI/180));//0.5000000000000001
console.log(Math.tan(45*Math.PI/180));//0.9999999999999999
console.log(Math.asin(1)*180/Math.PI);//90
console.log(Math.acos(1)*180/Math.PI);//0
console.log(Math.atan(1)*180/Math.PI);//45
console.log(Math.atan2(1,1)*180/Math.PI);//45

tips

[tips1] Find the maximum or minimum value in the array

var values = [1,2,3,4,5,6,7,8];
var max = Math.max.apply(Math,values);//8 

[tips2] Randomly select a value from a certain integer range

value = Math.floor(Math.random()*可能值的总数 + 第一个可能的值)

[tips3] Randomly select a value from the minimum and maximum values

function selectFrom(lowerValue,upperValue){
var choices = upperValue - lowerValue + 1;
return Math.floor(Math.random()*choices + lowerValue);
}
var num = selectFrom(2,10);
console.log(num); 

Math object method

Method	Description
abs(x)	Returns the absolute value of the number.
acos(x)	Returns the arc cosine of a number.
asin(x)	Returns the arcsine of the number.
atan(x)	Returns the arctangent of x as a number between -PI/2 and PI/2 radians.
atan2(y,x)	Returns the angle from the x-axis to the point (x,y) (between -PI/2 and PI/2 radians).
ceil(x)	對數進行上舍入。
cos(x)	傳回數的餘弦。
exp(x)	傳回 e 的指數。
floor(x)	對數進行下捨入。
log(x)	傳回數的自然對數（底為e）。
max(x,y)	傳回 x 和 y 中的最高值。
min(x,y)	傳回 x 和 y 中的最低值。
pow(x,y)	傳回 x 的 y 次方。
random()	傳回 0 ~ 1 之​​間的隨機數。
round(x)	把數四捨五入為最接近的整數。
sin(x)	傳回數的正弦。
sqrt(x)	傳回數的平方根。
tan(x)	返回角落的正切。
toSource()	傳回該物件的原始碼。
valueOf()	傳回 Math 物件的原始值。