javascript to ES6
模拟ES6的部分方法：
Number.[isFinite,isNaN,parseInt,parseFloat,isInteger]
Math.[trunc,sign,cbrt,fround,hypot,expm1,log1p,log10,log2]
Array.[form,of]
Array.prototype.[copyWithin,find,findIndex,fill,includes]
Function.prototype.[getLength]
String.prototype.[includes,startsWith,endsWith,repeat,padStart,padEnd,append,tag]
...