javaScript's toLocaleString() number formatting

Number.prototype.toLocaleString()

toLocaleString() The method returns the string representation of this number in a specific locale.

grammar:

numObj.toLocaleString([locales [, options]])

let num=12345678.98
num.toLocaleString()
//2,345,678.98

let num2=0.56
num2.toLocaleString('zh',{style:'percent'})
//'56%'


num2.toLocaleString('zh',{style:'currency',currency:'cny'})
//¥0.56

num2.toLocaleString('zh',{style:'currency',currency:'cny',currencyDisplay:'code'})
//'CNY 0.56'

num2.toLocaleString('zh',{style:'currency',currency:'cny',currencyDisplay:'name'})

//'0.56人民币'