Digits greater than or equal to 5 need not to be changed as changing them will lead to a smaller number
if ( str [ i ] < ' ' ) { var l = ( ' ' . charCodeAt ( 0 ) - str [ i ] . charCodeAt ( 0 ) ) + ' ' . charCodeAt ( 0 ) ; str2 = str2 . concat ( String . fromCharCode ( l ) ) ; } }