Kata JS

Even Or Odd :

function even_or_odd(number) {
  if (number % 2 === 0) return 'Even';
  return 'Odd';
}

console.log(even_or_odd(4)) // Even
console.log(even_or_odd(5)) // Odd

Opposite number :

function opposite(number) {
   return -number
}

console.log(opposite(5)) // -5

Remove first and last char of string :

function removeChar(str){
  return str.slice(1,(str.length - 1)) 
};

console.log(removeChar('eloquent')); // loquen;