javascript: Replace values in a string based on an array, efficient solution

Question

I have a sample code but I am looking for the most efficient solution. Sure I can loop twice through the array and string but I was wondering if I could just do a prefix search character per character and identify elements to be replaced. My code does not really do any of that since my regex is broken.

const dict = {
    '\\iota': 'ι',
    '\\nu': 'ν',
    '\\omega': 'ω',
    '\\\'e': 'é',
    '^e': 'ᵉ'
}
const value = 'Ko\\iota\\nu\\omega L\'\\\'ecole'

const replaced = value.replace(/\b\w+\b/g, ($m) => {
  console.log($m)
  const key = dict[$m]
  console.log(key)
  return (typeof key !== 'undefined') ? key : $m
})

Answer 1

Your keys are not fully word characters, so \b\w+\b will not match them. Construct the regex from the keys instead:

// https://stackoverflow.com/questions/3446170/escape-string-for-use-in-javascript-regex
const escapeRegExp = string => string.replace(/[.*+?^${}()|[\]\\]/g, '\\$&');

const dict = {
    '\\iota': 'ι',
    '\\nu': 'ν',
    '\\omega': 'ω',
    '\\\'e': 'é',
    '^e': 'ᵉ'
}
const value = 'Ko\\iota\\nu\\omega L\'\\\'ecole'

const pattern = new RegExp(Object.keys(dict).map(escapeRegExp).join('|'), 'g');
const replaced = value.replace(pattern, match => dict[match]);
console.log(replaced);