code: function phpEscape(s) {
    var result = '"';
    for (let cp of UnicodeUtils.getCodePoints(s)) {
      let special = specialEscape[cp];
      if (special !== undefined) {
        result += special;
      } else if (cp >= 0x20 && cp <= 0x7e) {
        result += String.fromCodePoint(cp);
      } else if (cp <= 0xFFFF) {
        result += '\\u{' + zeroPaddedHex(cp, 4) + '}';
      } else {
        result += '\\u{' + zeroPaddedHex(cp, 6) + '}';
      }
    }
    result += '"';
    return result;
  }
docs: Returns a double-quoted PHP string with all non-printable and
  non-US-ASCII sequences escaped.
  
  @param {string} str Valid Unicode string
  @return {string}    Double-quoted string with Unicode sequences escaped