pascal-ifying strings and arrays in JS

pascalify.js

function capitalize(str = '') {
  let cap = str.substring(0,1).toUpperCase();
  let rest = str.substring(1).toLowerCase();
  return `${cap}${rest}`
}

function toPascalCase(str = '') {
  let splitStr = str.split(' ');
  return splitStr.map(word => capitalize(word)).join('');
}

function pascalArr(arr = [], separator = '\n') {
  return arr.map((str) => {
    return toPascalCase(str)
  }).join(separator)
}