Answers for "how to i check the letters from the string it is uppercase or lowercase in javascript"

uppercase and lowercase letters in js

str.toLowerCase()
str.toUpperCase()

js test letter lowercase

if (character == character.toLowerCase())
{
  // The character is lowercase
}
else
{
  // The character is uppercase
}
//The problem with this answer is, 
//that some characters like numbers or punctuation 
//also return true when checked for lowercase/uppercase.

// this is the solution for it:
function isLowerCase(str)
{
    return str == str.toLowerCase() && str != str.toUpperCase();
}

how to find if given character in a string is uppercase or lowercase in javascript

var str = S;

  if (str == str.toUpperCase())
  {
    console.log(" Uppercase");
  }
  else
  {
    console.log("Lowercase");
  }