check lowercase in javascript code example

Example 1: javascript lowercase string

var str = "My Big Boy!"
var res = str.toLowerCase(); //res is "my big boy!"

Example 2: how to check string uppercase or lowersace using regex javascript

var regex = /^(?=.*[a-z])(?=.*[A-Z])(?=.*[0-9])(?=.*[!#\*\?])(?=.{8,})/;