Function strEscape

lib/internal/util/inspect.js:787–850

(str)

// Escape control characters, single quotes and the backslash.
// This is similar to JSON stringify escaping.
function strEscape(str) {
  let escapeTest = strEscapeSequencesRegExp;
  let escapeReplace = strEscapeSequencesReplacer;
  let singleQuote = 39;

  // Check for double quotes. If not present, do not escape single quotes and
  // instead wrap the text in double quotes. If double quotes exist, check for
  // backticks. If they do not exist, use those as fallback instead of the
  // double quotes.
  if (StringPrototypeIncludes(str, "'")) {
    // This invalidates the charCode and therefore can not be matched for
    // anymore.
    if (!StringPrototypeIncludes(str, '"')) {
      singleQuote = -1;
    } else if (!StringPrototypeIncludes(str, '`') &&
               !StringPrototypeIncludes(str, '${')) {
      singleQuote = -2;
    }
    if (singleQuote !== 39) {
      escapeTest = strEscapeSequencesRegExpSingle;
      escapeReplace = strEscapeSequencesReplacerSingle;
    }
  }

  // Some magic numbers that worked out fine while benchmarking with v8 6.0
  if (str.length < 5000 && RegExpPrototypeExec(escapeTest, str) === null)
    return addQuotes(str, singleQuote);
  if (str.length > 100) {
    str = RegExpPrototypeSymbolReplace(escapeReplace, str, escapeFn);
    return addQuotes(str, singleQuote);
  }

  let result = '';
  let last = 0;
  for (let i = 0; i < str.length; i++) {
    const point = StringPrototypeCharCodeAt(str, i);
    if (point === singleQuote ||
        point === 92 ||
        point < 32 ||
        (point > 126 && point < 160)) {
      if (last === i) {
        result += meta[point];
      } else {
        result += `${StringPrototypeSlice(str, last, i)}${meta[point]}`;
      }
      last = i + 1;
    } else if (point >= 0xd800 && point <= 0xdfff) {
      if (point <= 0xdbff && i + 1 < str.length) {
        const point = StringPrototypeCharCodeAt(str, i + 1);
        if (point >= 0xdc00 && point <= 0xdfff) {
          i++;
          continue;
        }
      }
      result += `${StringPrototypeSlice(str, last, i)}\\u${NumberPrototypeToString(point, 16)}`;
      last = i + 1;
    }
  }