Events and hooks

Run your code before or after specific data grid actions, using Handsontable's API hooks (callbacks). For example, control what happens with the user's input.

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Overview

Callbacks are used to react before or after actions occur. We refer to them as hooks. Handsontable's hooks share some characteristics with events and middleware, combining them both in a unique structure.

Events

If you only react to emitted hooks and forget about all their other features, you can treat Handsontable's hooks as pure events. You would want to limit your scope to after prefixed hooks, so they are emitted after something has happened and the results of the actions are already committed.

::: only-for react

<HotTable afterCreateRow={(row, amount) => {
  console.log(`${amount} row(s) were created, starting at index ${row}`);
}}/>

:::

::: only-for javascript

hot.addHook('afterCreateRow', (row, amount) => {
  console.log(`${amount} row(s) were created, starting at index ${row}`);
})

:::

::: only-for angular

hotTable.hotInstance.addHook("afterCreateRow", (row, amount) => {
  console.log(`${amount} row(s) were created, starting at index ${row}`);
});

:::

Middleware

Middleware is a concept known in the JavaScript world from Node.js frameworks such as Express or Koa. Middleware is a callback that can pipe to a process and allow the developer to modify it. We're no longer just reacting to an emitted event, but we can influence what's happening inside the component and modify the process.

::: only-for react

<HotTable modifyColWidth={(width, column) => {
    if (column > 10) {
      return 150;
    }
}}/>

:::

::: only-for javascript

hot.addHook('modifyColWidth', (width, column) => {
  if (column > 10) {
    return 150;
  }
})

:::

::: only-for angular

import { GridSettings } from "@handsontable/angular-wrapper";

gridSettings: GridSettings = {
  modifyColWidth: (width, column) => {
    if (column > 10) {
      return 150;
    }
  },
};

<hot-table [settings]="gridSettings" />

:::

Note that the first argument is the current width that we're going to modify. Later arguments are immutable, and additional information can be used to decide whether the data should be modified.

Handsontable hooks

We refer to all callbacks as "Handsontable hooks" because, although they share some characteristics with events and middleware, they combine them both in a unique structure. You may already be familiar with the concept as we're not the only ones that use the hooks convention.

Almost all before-prefixed Handsontable hooks let you return false and, therefore, block the execution of an action. It may be used for validation, rejecting operation by the outside service, or blocking our native algorithm and replace it with a custom implementation.

A great example for this is our integration with HyperFormula engine where creating a new row is only possible if the engine itself will allow it:

::: only-for react

<HotTable
  beforeCreateRow={(row, amount) => {
    if (!hyperFormula.isItPossibleToAddRows(0, [row, amount])) {
      return false;
    }
}}/>

:::

::: only-for javascript

hot.addHook('beforeCreateRow', (row, amount) => {
  if (!hyperFormula.isItPossibleToAddRows(0, [row, amount])) {
    return false;
  }
})

:::

::: only-for angular

import { GridSettings } from "@handsontable/angular-wrapper";

gridSettings: GridSettings = {
  beforeCreateRow: (row, amount) => {
    if (!hyperFormula.isItPossibleToAddRows(0, [row, amount])) {
      return false;
    }
  },
};

<hot-table [settings]="gridSettings" />

:::

The first argument may be modified and passed on through the Handsontable hooks that are next in the queue. This characteristic is shared between before and after hooks but is more common with the former. Before something happens, we can run the data through a pipeline of hooks that may modify or reject the operation. This provides many possibilities to extend the default Handsontable functionality and customize it for your application.

::: only-for react

External control

::: example #example3 :react --js 1 --ts 2 --css 3

@code @code @code

:::

:::

::: only-for angular

::: example #example3 :angular --ts 1 --html 2

@code @code

:::

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All available Handsontable hooks example

Note that some callbacks are checked on this page by default.

::: example-without-tabs #example1

@code @code @code

:::

Definition for source argument

It's worth mentioning that some Handsontable hooks are triggered from the Handsontable core and some from the plugins. In some situations, it is helpful to know what triggered the callback. Did Handsontable trigger it, or was it triggered by external code or a user action? That's why in crucial hooks, Handsontable delivers source as an argument informing you who triggered the action and providing detailed information about the source. Using the information retrieved in the source, you can create additional conditions.

source argument is optional. It takes the following values:

List of callbacks that operate on the source parameter:

• afterChange
• afterCreateCol
• afterCreateRow
• afterLoadData
• afterSetDataAtCell
• afterSetDataAtRowProp
• afterSetSourceDataAtCell
• afterRemoveCol
• afterRemoveRow
• afterValidate
• beforeChange
• beforeChangeRender
• beforeCreateCol
• beforeCreateRow
• beforeLoadData
• beforeRemoveCol
• beforeRemoveRow
• beforeValidate

The beforeKeyDown callback

The following demo uses beforeKeyDown callback to modify some key bindings:

• Pressing <kbd>Delete</kbd> or <kbd>Backspace</kbd> on a cell deletes the cell and shifts all cells beneath it in the column up resulting in the cursor, which doesn't move, having the value previously beneath it, now in the current cell.
• Pressing <kbd>Enter</kbd> in a cell where the value remains unchanged pushes all the cells in the column beneath and including the current cell down one row. This results in a blank cell under the cursor which hasn't moved.

::: only-for javascript

::: example #example2 --js 1 --ts 2

@code @code

:::

:::

::: only-for react

::: example #example2 :react --js 1 --ts 2

@code @code

:::

:::

::: only-for angular

::: example #example2 :angular --ts 1 --html 2

@code @code

:::

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Related API reference

• Core methods:
  • addHook()
  • addHookOnce()
  • hasHook()
  • removeHook()
  • hasHook()
  • runHooks()
• Hooks:
  • List of all Handsontable hooks
  • afterListen
  • afterUnlisten