SpreadJS supports extending the pasted range if the pasted range is not enough for the pasted data. This can give users more freedom with the amount of cells that can be pasted.
If you want to use this feature, just set the workbook allowExtendPasteRange option to true. For example:
workbook.options.allowExtendPasteRange = true;
Then SpreadJS will extend the paste range if the paste range is not large enough for data. The default value is false