Highcharts TypeScript Declarations

Highcharts provides integrated support for TypeScript through bundled declarations files. TypeScript-compatible editors can give you tooltips and suggestions for Highcharts as you type. The TypeScript compiler watches and points out potential problems while coding. The outcome is a faster and better fail-proofed development cycle for your Highcharts-based solutions.

Installation

You need a TypeScript-capable Editor, like Microsoft's Visual Studio Code, for getting autocompletion and hints for Highcharts. Please note that Highcharts contains comprehensive declarations, which makes increased memory usage in a few editors like Webstorm necessary. The declarations are part of the Highcharts NPM package. The Highcharts NPM package can be installed in your project folder with npm install highcharts.

Configuration

TypeScript

Highcharts is a charting library most often used in the web browser and in that case you probably need to modify the TypeScript configuration for the target platform. The tsconfig.json below, covers a typical use case of Highcharts:

{
    "compilerOptions": {
        "strict": true,
        "target": "es2020",
        "module": "es6",
        "moduleResolution": "node",
        "outDir": "mychart/",
    },
    "exclude": [
        "node_modules"
    ]
}

If you place your TypeScript source code (*.ts) in one of your project folders, the TypeScript compiler will automatically find it, compile it and output the JavaScript compiled code (*.js) to the outDir folder.

With the exclude property you prevent specified folders from compiling to TypeScript, for example files found in the node_modules folder.

RequireJS

Not every web browser is capable to load ES6 modules. Here comes RequireJS for a compiler target of AMD into action. It needs some configuration to support the Highcharts package:

require.config({
    packages: [{
        name: 'highcharts',
        main: 'highcharts'
    }],
    paths: {
        'highcharts': 'https://code.highcharts.com'
    }
})

For Highcharts Stock and other additions it is recommended to use the previous configuration and load the module (highcharts/modules/stock) instead. For the package you have to change the configuration in the following way:

require.config({
    packages: [{
        name: 'highcharts',
        main: 'highstock'
    }],
    paths: {
        'highcharts': 'https://code.highcharts.com/stock'
    }
})

Details about the configuration options can be found in the RequireJS documentation.

Using Highcharts Typing

There are some subtle differences in using the Highcharts product bundles and the modules, either in classic namespace-based projects or as ES-module-based projects.

Highcharts Bundles

Starting point is one of the product bundles in the Highcharts NPM package. Best practice is to always use the default product bundle in TypeScript projects. This avoids conflicts between competing product bundles.

  • For classic projects use:

    import Highcharts from 'highcharts';

  • For ES module projects use:

    import Highcharts from 'highcharts/es-modules/masters/highcharts';

Other possible product bundles are:

  • ../highcharts-gantt
  • ../highmaps
  • ../highstock

Highcharts Modules

With the help of Highcharts modules you can extend a Highcharts bundle with additional functionality, for example to provide A11y controls.

  • For classic projects use:

    import Accessibility from 'highcharts/modules/accessibility';
    Accessibility(Highcharts);

  • For ES module projects use:

    import Accessibility from 'highcharts/es-modules/masters/modules/accessibility';

Extending Highcharts Typing

The Highcharts libraries come with a huge amount of possibilities right out of the box, but for a special use case you might need to extend default behavior of Highcharts. Extending Highcharts in TypeScript follows a straightforward pattern as illustrated with the below example.

Steps

  • Use proper typing in your extensions
  • Declare additional interfaces of your extensions in the Highcharts namespace
  • Make use of existing Highcharts types and interfaces
  • For a deep dive into TypeScript declarations take a look at the official TypeScript guide.

Example

If you like to have a custom highlight function for you data points, you could come up with the following code. You might notice, that the beginning code is actually not real TypeScript and instead is just common ECMAScript, widely known as JavaScript:

import * as Highcharts from 'highcharts';
Highcharts.Point.prototype.highlight = function (event) {
    event = this.series.chart.pointer.normalize(event);
    this.onMouseOver(event);
    this.series.chart.tooltip.refresh(this);
    this.series.chart.xAxis[0].drawCrosshair(event, this);
};

First you have to make TypeScript aware of the types in your function, so you have to specify the type of the event parameter in this example:

// ...
Highcharts.Point.prototype.highlight = function (
    event: Highcharts.PointerEvent
): void {
// ...

Secondly assure TypeScript, that creating a new function on Highcharts.Point is really made by intention. You can do this with declarations for the Highcharts namespace - in a separate file like ./global.d.ts or directly in your code:

// ...
declare module 'highcharts' {
    interface Point {
        highlight (event: Highcharts.PointerEventObject): void;
    }
}
// ...

Finally the source code of the example would look like this:

import * as Highcharts from 'highcharts';
declare module 'highcharts' {
    interface Point {
        highlight (event: Highcharts.PointerEventObject): void;
    }
}
Highcharts.Point.prototype.highlight = function (
    event: Highcharts.PointerEvent
): void {
    event = this.series.chart.pointer.normalize(event);
    this.onMouseOver(event);
    this.series.chart.tooltip.refresh(this);
    this.series.chart.xAxis[0].drawCrosshair(event, this);
};

Note: If you like to replace existing functionality of Highcharts, listen to the Highcharts events instead of overwriting functions and methods. That way you can avoid many unintended side effects.

Project Migration

Migration from JavaScript

For full fail-proofed development you may convert your project's source code to TypeScript. The initial step is:

npm install typescript && npx tsc --init

More information about migrating JavaScript projects to TypeScript can be found in the official TypeScript handbook.

Migration from Definitely Typed

If you previously used TypeScript declarations for Highcharts like @types/highcharts, you should uninstall them to prevent any mismatch:

npm uninstall @types/highcharts

Solving Problems

Debugging

If TypeScript is complaining about your Highcharts options, then it might not find the correct series as a reference. If that is the case, cast the series options explicitly to the desired type and you get more helpful error messages:

series: [{
    type: "line",
    data: [1, 2, "3", 4, 5]
} as Highcharts.LineSeriesOptions]

Reporting Bugs

Highcharts TypeScript declarations are in a beta state. They can be used in production, but will bring breaking changings in a future major version. In that case, some modifications to the types will be necessary. If you found something in TypeScript that is not working as in our documentation or demos, you can create an issue report to inform us.

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