(Under development)

Usage no npm install needed!

<script type="module">
  import streaksheet from '';



(Under development)

TODO some of the content here is for internal use. We should move that to a separate file and make this file be for users.


Important: StreakSheet requires the browser to support AbortController, so if you need to support browsers that predate it (, you must first load a global polyfill.


To run the example:

yarn example-watch

Then open http://localhost:1234 in your browser. The page automatically refreshes after making a change.


TODO Incomplete

These methods exist on refs to StreakSheet components.

  • enterEditMode(sectionKey, columnKey, rowKey, queuedValue?).

    If you pass a value for the optional 3rd parameter, then the value will be passed to the Cell as the initialEditQueuedValue prop.

    NOTE for users: if you pass a React synthetic event as 3rd parameter, call .persist() on it first. (This will be unnecessary in React 17+.)

Cell Event Handling

When a cell is in edit mode, StreakSheet ignores arrow key inputs, so that moving the cursor around inside a text input inside the cell doesn't move the cursor in the spreadsheet. However, StreakSheet continues to react to escape, enter, shift-enter, tab, and shift-tab key presses. If you want to handle those events yourself when an element inside of a cell is focused, then set up your own event listener to handle the keypress and call the stopPropagation() method on the event, which will stop StreakSheet from reacting to it.


These are props that should be passed to the StreakSheet component.

TODO Incomplete list here

  • onEnterEditMode(event: {sectionKey, columnKey, rowKey, cancel})

Optional. This prop allows you to prevent some cells from being able to be switched into edit mode by calling the cancel method on the event object.

Note: rowKey may be null if the user is attempting to enter edit mode on a section row header.

  • onUnhandledKeyDown(event: {domEvent, sectionKey, columnKey, rowKey})

Optional. When a key is pressed that StreakSheet doesn't specifically handle while a cell is selected but no cells are in edit mode, this function is called. If the cell is meant to be editable and support text input, then you may pass a function which calls event.domEvent.persist() and then enterEditMode(sectionKey, columnKey, rowKey, event.domEvent) on the StreakSheet ref to put the cell into edit mode and set its initialEditQueuedValue prop, so you can process the keydown event inside the cell when it first renders in edit mode.

  • Cell

You must pass a React component that takes the following props:

columnKey: string;
isEditing: boolean;
setEditing(isEditing: boolean): void;
initialEditQueuedValue: unknown | undefined;
rowData: T;
rowKey: string;

The initialEditQueuedValue prop is present when the cell is switched into edit mode with enterEditMode(), and includes the queuedValue parameter value. The initialEditQueuedValue prop should only be read when a component first switches into edit mode.


Separate from props, the useSheetData hook provides a convenient interface that one uses to asynchronously supply the sheet with row data.


The return value of useSheetData has the following methods:

  • getRowData(sectionKey: string, rowKey: string): T | undefined

    Returns the rowData for a given sectionKey, rowKey pair or undefined if a row could not be found.

  • addRowData(sectionKey: string, rowKey: string, rowData: T, afterRowKey?: string): boolean

    afterRowKey indicates a row after which the user would like to place the new row. Ignore this parameter to insert the new row at the beginning of the section.

    Returns a boolean for whether the addition was successful. The addition would not succeed, for example, if the provided sectionKey referred to a section not currently found in the spreadsheet.

  • deleteRowData(sectionKey: string, rowKey: string): boolean;

    Returns a boolean for whether the deletion was successful. A deletion would not succeed if a row to delete could not be found for the sectionKey, rowKey pair.


You can provide custom styles for most components via the styles prop. Each value of this object in an optional function. The first argument is the default styles and the second is an object of state values specific to that component. The return value is a CSSProperties object.

(base: CSSProperties, state: {}) => CSSProperties;

You can choose to extend the default styles or replace them completely. You almost always want to do the former.

  columnReorderOverlay: base => ({
    backgroundColor: 'red',

Be careful when overriding styles completely. Many components apply rules like position: absolute that will break the component if removed.

The Styles type indicates exactly what state values each style callback sends. Some components are unaffected by state, in which case the second argument is omitted completely.

  columnResizeHandle: (base, { isDragging }) => ({
    backgroundColor: isDragging ? 'red' : 'blue',

This API is inspired by React Select

Selection Styles

For each selection type there are actually two styles to apply: one for the foreground, another for the background. Typically you want to apply a backgroundColor rules to the background style and borders to the foreground. This prevents elements like images from getting discolored by a partially transparent background overlaying it.

  selectionBackground: base => ({
    backgroundColor: 'red',
  selectionForeground: base => ({
    borderTop: '1px dashed blue',

Overriding Borders

When applying custom border styles, it's common to want different styles for different edges. To make overriding default styles easier, internally we use borderBottom, borderLeft, borderRight, and borderTop shorthand, even when all four rules have the same value.

  columnHeaderCellContainer: (base, { columnIndex }) => ({
    // Make border between cells 1px while keeping border on leftmost cell.
    borderLeft: columnIndex === 0 ? '1px solid black' : 'none',

Style Keys

  • cell
  • cellEditMode
  • columnHeaderCellContainer
  • columnHeadersContainer
  • columnReorderIndicator
  • columnReorderOverlay
  • columnResizeHandle
  • columnResizeIndicator
  • copiedRegionBackground
  • copiedRegionForeground
  • grid
  • highlightedRowBackground
  • highlightedRowForeground
  • primarySelectedCellBackground
  • primarySelectedCellForeground
  • sectionHeaderCellContainer
  • sectionHeadersContainer
  • selectionBackground
  • selectionForeground

Keys vs. Indexes

StreakSheet internally often uses row and column indexes to refer to a cell. For example, the selection logic uses indexes and has no knowledge of sections.

The client never deals with indexes. Instead, section, row, and column keys uniquely identify each cell. In callbacks like onPaste and imperative methods like getSelectedCells, cells are represented by objects:

  sectionKey: string;
  rowKey: string;
  columnKey: string;

Internally, a cellIndexesToKeys function converts raw grid indexes to cell keys.


There are multiple ways a cell can appear selected.

It may be sufficient to override the default styles for the various selections, but you can also get the current selection using the imperative getSelectedCells method.

const selectedCells = sheetRef.current.getSelectedCells();

Primary Selected Cell

The first cell of each selection region is the "primary" selected cell. It acts as the anchor when expanding the selection region using the keyboard. When you click on the grid and there's a single cell selected, this is the primary one.

You can change the primary selected cell by clicking on any cell or using the arrow keys.

Selection Region

Clicking and dragging or using shift + arrow keys allows you to select multiple cells.

It's possible to have multiple selection regions by holding command while dragging.

Highlighted Row

All the cells in the same row as the primary selected cell appear highlighted. This isn't a selection per se, more a visual decoration.

Copied Region

When some cells are selected and you hit command-c to copy them, the copied region is indicated until the user pastes or copies a different region.

Copying Cells

StreakSheet supports the ability to copy and paste regions of cells. Clients listen for a paste event by supplying an onPaste to the useSheetData hook.

Upon being notified of a paste, it's up to the client to update the data accordingly. StreakSheet takes care of mapping the source cells to target cells.

onPaste: pasteTargets => {
  // pasteTargets is an array of objects with source and target keys.
  // [
  //   {
  //     source: { sectionKey: 'a', 'rowKey: 'b', columnKey: 'c' },
  //     target: { sectionKey: 'd', 'rowKey: 'e', columnKey: 'f' },
  //   },
  //   ...
  // ]

The onPaste callback has a second argument didCut which indicates if the user used command-x rather than command-c to copy the selection. Again, it's up to the client to update the source cells (or not, depending on the desired behaviour).

When the paste region is larger than the copy region (i.e. the user copies a range, selects a larger range, then pastes), the copied values are "looped". That is, a 2x2 region pasted to a 3x3 region will result in this:

┏━━━━━┳━━━━━┓ ┏━━━━━┳━━━━━┳━━━━━┓
┃  A  ┃  B  ┃ ┃  A  ┃  B  ┃  A  ┃
┣━━━━━╋━━━━━┫ ┣━━━━━╋━━━━━╋━━━━━┫
┃  C  ┃  D  ┃ ┃  C  ┃  D  ┃  C  ┃
┗━━━━━┻━━━━━┛ ┣━━━━━╋━━━━━╋━━━━━┫
              ┃  A  ┃  B  ┃  A  ┃

The resulting pasteTargets will have nine entries. Assuming the copy region starts at [row 0, column 0] and the selection region at [row 10, column 10], the list will be:

  { source: {..., rowKey: '0', columnKey: '0'}, target: {..., rowKey: '10', columnKey: '10'} },
  { source: {..., rowKey: '0', columnKey: '1'}, target: {..., rowKey: '10', columnKey: '11'} },
  { source: {..., rowKey: '0', columnKey: '0'}, target: {..., rowKey: '10', columnKey: '12'} },
  { source: {..., rowKey: '1', columnKey: '0'}, target: {..., rowKey: '11', columnKey: '10'} },
  { source: {..., rowKey: '1', columnKey: '1'}, target: {..., rowKey: '11', columnKey: '11'} },
  { source: {..., rowKey: '1', columnKey: '0'}, target: {..., rowKey: '11', columnKey: '12'} },
  { source: {..., rowKey: '0', columnKey: '0'}, target: {..., rowKey: '12', columnKey: '10'} },
  { source: {..., rowKey: '0', columnKey: '1'}, target: {..., rowKey: '12', columnKey: '11'} },
  { source: {..., rowKey: '0', columnKey: '0'}, target: {..., rowKey: '12', columnKey: '12'} },