I'm using the following function to replace emojis in a string and is working great:
function doEmoji(s){
    var ranges = [
        '\ud83c[\udf00-\udfff]', // U+1F300 to U+1F3FF
        '\ud83d[\udc00-\ude4f]', // U+1F400 to U+1F64F
        '\ud83d[\ude80-\udeff]'  // U+1F680 to U+1F6FF
    ];
    var x = s.toString(16).replace(new RegExp(ranges.join('|'), 'g'),' whatever ');
    return x;
};
Now I want to check if that string only contains emojis or space characters. The reason why I want to do this is because I want to replace emojis only if no other characters are present(except space).
Some examples:
Hello how are you?  //do nothing
 // replace emojis
  // replace emojis
I'm looking for a simple solution, a regex maybe. Thanks