Method [kTabCompleter]

lib/internal/readline/interface.js:716–784

(lastKeypressWasTab, { 0: completions, 1: completeOn })

  }

  [kTabCompleter](lastKeypressWasTab, { 0: completions, 1: completeOn }) {
    // Result and the text that was completed.

    if (!completions || completions.length === 0) {
      return;
    }

    // If there is a common prefix to all matches, then apply that portion.
    const prefix = commonPrefix(
      ArrayPrototypeFilter(completions, (e) => e !== ''),
    );
    if (StringPrototypeStartsWith(prefix, completeOn) &&
        prefix.length > completeOn.length) {
      this[kInsertString](StringPrototypeSlice(prefix, completeOn.length));
      return;
    } else if (!StringPrototypeStartsWith(completeOn, prefix)) {
      this[kSetLine](StringPrototypeSlice(this.line,
                                          0,
                                          this.cursor - completeOn.length) +
                  prefix +
                  StringPrototypeSlice(this.line,
                                       this.cursor,
                                       this.line.length));
      this.cursor = this.cursor - completeOn.length + prefix.length;
      this[kRefreshLine]();
      return;
    }

    if (!lastKeypressWasTab) {
      return;
    }

    this[kBeforeEdit](this.line, this.cursor);

    // Apply/show completions.
    const completionsWidth = ArrayPrototypeMap(completions, (e) =>
      getStringWidth(e),
    );
    const width = MathMaxApply(completionsWidth) + 2; // 2 space padding
    let maxColumns = MathFloor(this.columns / width) || 1;
    if (maxColumns === Infinity) {
      maxColumns = 1;
    }
    let output = '\r\n';
    let lineIndex = 0;
    let whitespace = 0;
    for (let i = 0; i < completions.length; i++) {
      const completion = completions[i];
      if (completion === '' || lineIndex === maxColumns) {
        output += '\r\n';
        lineIndex = 0;
        whitespace = 0;
      } else {
        output += StringPrototypeRepeat(' ', whitespace);
      }
      if (completion !== '') {
        output += completion;
        whitespace = width - completionsWidth[i];