Transactions

api.applyTransaction({ add, update, remove }) applies a batch of row mutations in a single data update - one re-render for the whole batch, not one per row. It's the path to use for high-frequency / streaming feeds (WebSocket deltas, tick data) where calling addRow / setCellValue per row would thrash.

const result = api.applyTransaction({
  add:    [newOrder],                          // appended
  update: [{ ...order, price: nextPrice }],    // matched by id
  remove: ['ORD-1001', staleRowRef],           // by id OR row reference
})
// result -> { added: 1, updated: 1, removed: 2 }

Matching

• add - rows are appended to the data.
• update - each row is matched to an existing row by id, then replaced. Set getRowId so the grid can compute ids; without it, updates can't be matched.
• remove - accepts row ids (needs getRowId) and/or row object references (always works). Unknown ids are silently ignored.

The call returns the counts actually applied, so you can log or reconcile.

Why batch

Each applyTransaction produces exactly one new data array and therefore one reactive update, regardless of how many rows changed. On a live feed that emits dozens of deltas per second, batching them per animation frame (or per WebSocket message) keeps the grid smooth where per-row calls would not.

// buffer deltas, flush once per frame
let buffer: Delta[] = []
socket.onmessage = (e) => { buffer.push(JSON.parse(e.data)); schedule() }

function schedule() {
  requestAnimationFrame(() => {
    api.applyTransaction({
      add:    buffer.filter((d) => d.type === 'add').map((d) => d.row),
      update: buffer.filter((d) => d.type === 'update').map((d) => d.row),
      remove: buffer.filter((d) => d.type === 'remove').map((d) => d.id),
    })
    buffer = []
  })
}

Notes

• The grid owns its data after mount; read the current rows back with api.getData() (which reflects applied transactions).
• Selection, expansion, and edit state keyed by getRowId survive a transaction - that's the point of a stable row id.

See the live Transaction API demo.