hey VincyJelsingh ,
The following expression is rather complex and ugly looking but it does the job. If I think of a simpler solution, I will add it as well, but for now you can use this one.
['A','A','a','a','a','a'].map((x,index)=>
x==x.toUpperCase()? ['A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z'][Math.floor(Math.random()*15)] : ['a', 'b','c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's','t', 'u', 'v', 'w', 'x', 'y', 'z'][Math.floor(Math.random()*10)*2]).concat(['!', '@', '#', '$', '%', '^', '&', '*', '(', ')', '+', '-', '.', '~', '|', '<', '>', '=', '-', '_', '/', ':', ';', '?', '[', ']', '{', '}', '~'][Math.floor(Math.random()*15)]).concat(['0', '1', '2', '3', '4', '5', '6', '7', '8', '9'][Math.floor(Math.random()*10)])