NamingConvence

function solve() {

  let library = {
    'Camel Case': function (input) {
      return input.map((e, i) => {
        if (i === 0) {
          return e.toLowerCase();
        } else {
          let result = e[0].toUpperCase() + e.slice(1).toLowerCase();

          return result;
        }
      }).join('');

    },
    'Pascal Case': function (input) {
      return input.map(e => e[0].toUpperCase() + e.slice(1).toLowerCase()).join('');
    }
  };

  let textTokens = document.getElementById('text').value.split(' ');
  let namingCase = document.getElementById('naming-convention').value;

  if(library[namingCase]){
    document.getElementById('result').textContent = library[namingCase](textTokens);
  } else {
    document.getElementById('result').textContent = 'Error!';
  }

}