Method [kAddNewLineOnTTY]

lib/internal/readline/interface.js:966–1055

()

  // No matter where the new line was entered.
  // This function should only be used when the output is a TTY
  [kAddNewLineOnTTY]() {
    // Restore terminal state and store current line
    this[kRestorePreviousState]();
    const originalLine = this.line;

    // Split the line at the current cursor position
    const beforeCursor = StringPrototypeSlice(this.line, 0, this.cursor);
    let afterCursor = StringPrototypeSlice(this.line, this.cursor, this.line.length);

    // Add the new line where the cursor is at
    this[kSetLine](`${beforeCursor}\n${afterCursor}`);

    // To account for the new line
    this.cursor += 1;

    const hasContentAfterCursor = afterCursor.length > 0;
    const cursorIsNotOnFirstLine = this.prevRows > 0;
    let needsRewriteFirstLine = false;

    // Handle cursor positioning based on different scenarios
    if (hasContentAfterCursor) {
      const splitBeg = StringPrototypeSplit(beforeCursor, '\n');
      // Determine if we need to rewrite the first line
      needsRewriteFirstLine = splitBeg.length < 2;

      // If the cursor is not on the first line
      if (cursorIsNotOnFirstLine) {
        const splitEnd = StringPrototypeSplit(afterCursor, '\n');

        // If the cursor when I pressed enter was at least on the second line
        // I need to completely erase the line where the cursor was pressed because it is possible
        // That it was pressed in the middle of the line, hence I need to write the whole line.
        // To achieve that, I need to reach the line above the current line coming from the end
        const dy = splitEnd.length + 1;

        // Calculate how many Xs we need to move on the right to get to the end of the line
        const dxEndOfLineAbove = (splitBeg[splitBeg.length - 2] || '').length + kMultilinePrompt.description.length;
        moveCursor(this.output, dxEndOfLineAbove, -dy);

        // This is the line that was split in the middle
        // Just add it to the rest of the line that will be printed later
        afterCursor = `${splitBeg[splitBeg.length - 1]}\n${afterCursor}`;
      } else {
        // Otherwise, go to the very beginning of the first line and erase everything
        const dy = StringPrototypeSplit(originalLine, '\n').length;
        moveCursor(this.output, 0, -dy);
      }

      // Erase from the cursor to the end of the line
      clearScreenDown(this.output);

      if (cursorIsNotOnFirstLine) {
        this[kWriteToOutput]('\n');
      }
    }

    if (needsRewriteFirstLine) {
      this[kWriteToOutput](`${this[kPrompt]}${beforeCursor}\n${kMultilinePrompt.description}`);