fuzzysearch.js

function fuzzysearch (needle, haystack) {
  var hlen = haystack.length
  var nlen = needle.length
  if (nlen > hlen) {
    return false
  }
  if (nlen === hlen) {
    return needle === haystack
  }
  outer: for (var i = 0, j = 0; i < nlen; i++) {
    var nch = needle.charCodeAt(i)
    while (j < hlen) {
      if (haystack.charCodeAt(j++) === nch) {
        continue outer
      }
    }
    return false
  }
  return true
}

fuzzysearch2.js

function fuzzysearch2 (needle, haystack) {
  var haystackArray = Array.from(haystack)
  var needleArray = Array.from(needle)
  if (needleArray.length > haystackArray.length) {
    return false
  }
  if (needleArray.length === haystackArray.length) {
    return needle === haystack // Not unicode friendly.
  }
  var haystackSymbol = haystackArray.shift()
  var foundNeedle = needleArray.reduce((acc, needleSymbol) => {
    while (haystackSymbol && haystackSymbol !== needleSymbol) { // Not unicode friendly.
      haystackSymbol = haystackArray.shift()
    }
    if (haystackSymbol === needleSymbol) { // Not unicode friendly.
      acc += needleSymbol
    }
    return acc
  }, '')
  return needle === foundNeedle
}