SecondaryClipboard.js

var SecondaryClipboard = {
  cut: function(editorState: EditorState): EditorState {
    var content = editorState.getCurrentContent();
    var selection = editorState.getSelection();
    var targetRange: ?SelectionState = null;

    if (selection.isCollapsed()) {
      var anchorKey = selection.getAnchorKey();
      var block = content.getBlockForKey(anchorKey);
      var blockEnd = block.getLength();

      // Delete the block if it is empty
      if (blockEnd === 0) {
        return // TODO
      }

      // Delete from cursor to next newline or block end
      var restText = block.getText().slice(selection.getStartOffset())
      var nextNewlineIdx = restText.indexOf('\n')

      var cutUntilOffset
      if (nextNewlineIdx === 0) {
        // If next char is the newline, delete it and stop
        cutUntilOffset = selection.getStartOffset() + 1
      } else if (nextNewlineIdx > -1) {
        // If rest of string has a newline, delete until it
        cutUntilOffset = nextNewlineIdx + selection.getStartOffset()
      } else {
        cutUntilOffset = blockEnd
      }

      targetRange = selection.set('focusOffset', cutUntilOffset);
    } else {
      targetRange = selection;
    }

    targetRange = nullthrows(targetRange);
    clipboard = getContentStateFragment(content, targetRange);

    var afterRemoval = DraftModifier.removeRange(
      content,
      targetRange,
      'forward',
    );

    if (afterRemoval === content) {
      return editorState;
    }

    return EditorState.push(editorState, afterRemoval, 'remove-range');
  },