Math mathematical object
The Math object is a static object. In other words: when using the Math object, there is no need to create an instance.
Math.PI: Pi.
Math.abs(): Absolute value. For example: Math.abs(-9) = 9
Math.ceil(): round up (add 1 to the integer and remove the decimal). For example: Math.ceil(10.2) = 11
Math.floor(): Round down (remove decimals directly). For example: Math.floor(9.888) = 9
Math.round(): Rounding. For example: Math.round(4.5) = 5; Math.round(4.1) = 4
Math.pow(x,y): Find the yth power of x. For example: Math.pow(2,3) = 8
Math.sqrt(): Find the square root. For example: Math.sqrt(121) = 11
Math.random(): Returns a random decimal between 0 and 1. For example: Math.random() = 0.12204467732259783
Note: Find a random number between (min, max). The formula is: Math.random()*(max-min)+min
Example: Random integer between 0-10; find random number between 10-20 Integer; Find a random integer between 20 and 30; Find a random integer between 7 and 91
<!DOCTYPE HTML> <html> <head> <meta http-equiv="Content-Type" content="text/html; charset=utf-8"> <title>php.cn</title> <script> //求两个整数之间的随机整数 //定义随机数的函数 function getRandom(min,max){ //求随机数 var random =Math.random()*(max-min)+min; //向下取整 random = Math.floor(random); //输出结果 document.write(random+"<hr>"); } //调用函数 getRandom(0,100); getRandom(5,89); getRandom(100,999); </script> </head> <body> </body> </html>
Example: Random web page background color
<!DOCTYPE HTML> <html> <head> <meta http-equiv="Content-Type" content="text/html; charset=utf-8"> <title>php.cn</title> </head> <body> </body> </html> <script> var min = 100000; var max = 999999; var random = Math.random() *(max-min)+min; //向下取整 random = Math.floor(random); document.body.bgColor = "#"+random; </script>Next Section