Capitalize first letter of each word in JS

Question

I\'m learning how to capitalize the first letter of each word in a string and for this solution I understand everything except the word.substr(1) portion. I see that it\'s a

Answer 1

const capitalize = str => {
  if (typeof str !== 'string') {
    throw new Error('Invalid input: input must of type "string"');
  }

  return str
    .trim()
    .replace(/ {1,}/g, ' ')
    .toLowerCase()
    .split(' ')
    .map(word => word[0].toUpperCase() + word.slice(1))
    .join(' ');
};

• sanitize the input string with trim() to remove whitespace from the leading and trailing ends

• replace any extra spaces in the middle with a RegExp

• normalize and convert it all toLowerCase() letters

• convert the string to an array split on spaces

• map that array into an array of capitalized words

• join(' ') the array with spaces and return the newly capitalized string