removeAccents.js

const removeAccents = (function () {
  const dictionary = {
    a: 'àáảãạăằắẳẵặâầấẩẫậ', e: 'èéẻẽẹêềếểễệ', i: 'ìíỉĩị', o: 'òóỏõọôồốổỗộơờớởỡợ', u: 'ùúủũụưừứửữự', d: 'đ',
    A: 'ÀÁẢÃẠĂẰẮẲẴẶÂẦẤẨẪẬ', E: 'ÈÉẺẼẸÊỀẾỂỄỆ', I: 'ÌÍỈĨỊ', O: 'ÒÓỎÕỌÔỒỐỔỖỘƠỜỚỞỠỢ', U: 'UÙÚỦŨỤƯỪỨỬỮỰ', D: 'Đ'
  }
  const convertMap = {}
  for (const key of Object.keys(dictionary)) {
    for (const char of dictionary[key]) {
      convertMap[char] = key
    }
  }
  return function (text) {
    let output = ''
    for (const char of text) {
      output += convertMap[char] || char
    }
    return output
  }
})()