Method setPreviousStatement

packages/blockly/core/block.ts:1251–1277

* Set whether this block can chain onto the bottom of another block. * * @param newBoolean True if there can be a previous statement. * @param opt_check Statement type or list of statement types. Null/undefined * if any type could be connected.

(
    newBoolean: boolean,
    opt_check?: string | string[] | null,
  )

   *     if any type could be connected.
   */
  setPreviousStatement(
    newBoolean: boolean,
    opt_check?: string | string[] | null,
  ) {
    if (newBoolean) {
      if (opt_check === undefined) {
        opt_check = null;
      }
      if (!this.previousConnection) {
        this.previousConnection = this.makeConnection_(
          ConnectionType.PREVIOUS_STATEMENT,
        );
      }
      this.previousConnection.setCheck(opt_check);
    } else {
      if (this.previousConnection) {
        if (this.previousConnection.isConnected()) {
          throw Error(
            'Must disconnect previous statement before removing ' +
              'connection.',
          );
        }
        this.previousConnection.dispose();
        this.previousConnection = null;
      }
    }
  }

  /**
   * Set whether another block can chain onto the bottom of this block.