When writing a custom Jupyter Widget, sometimes you need to know the Cell (CodeCell, usually) that your Widget is running in. You can get a list of all Cells from the Notebook object in Javascript, but finding your Cell isn’t exactly that straight-forward.
Fortunately, it isn’t that hard to determine your Cell, since you can find the container element for your Widget, and then loop through all Cells in the Notebook to see which one you are in:
const container = this.$el.parents('.cell');
const cell = this.notebook.get_cells().find(it => it.element.is(container));
If all goes well, cell will contain your Cell object.