@webext-pegasus/rpc
v0.3.6
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RPC Messaging in Web Extensions made easy and type safe. Out of the box.
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@webext-pegasus/rpc
RPC Messaging in Web Extensions made easy and type safe. Out of the box. It provides a simple type-safe wrapper around the web extension messaging APIs that lets you call a function/class from anywhere, but execute it in the target runtime context.
Supports
- Runtime contexts: window (injected script), popup, devtools, content script, background, options, sidepanel (planned)
- Browsers: Chrome, Firefox, Safari, Opera, Edge + others supported by webextension-polyfill
🚀 Quick Start
npm install -S @webext-pegasus/transport @webext-pegasus/rpc
- Create service in a form of a class or function that implements
IPegasusRPCService<YourService>
- Export TypeScript interface for it
- Register interface via
registerRPCService('serviceName', yourService)
in the target runtime context (ex: background) - Acquire service wrapper via
getRPCService<YourServiceType>('serviceName', 'background')
- That's it! Now you can call it from any other place in your extension!
[!TIP] Refer to ./packages/example-extension for more examples.
MathService.ts
import {IPegasusRPCService, PegasusRPCMessage} from '@webext-pegasus/rpc';
export type IMathService = InstanceType<
typeof MathService
>;
export class MathService
implements IPegasusRPCService<MathService>
{
// Every public method shall:
// - accept "sender: PegasusRPCMessage" as first parameter, if it accepts any params
// - accept / return only serializable values, as RPC messages must be serialized as they move between extension contexts
// See "./src/types.test.ts" for more examples
fibonacci(_sender: PegasusRPCMessage, num: number): number {
return this.#fibonacciImpl(num);
}
// We keep implemenation in private method as we don't need sender information here
#fibonacciImpl(num: number): number {
return (num <= 1) ? 1 : this.#fibonacciImpl(num - 1) + this.#fibonacciImpl(num - 2);
}
}
background.ts
import {registerRPCService} from '@webext-pegasus/rpc';
import {initPegasusTransport} from '@webext-pegasus/transport/background';
import {MathService} from './MathService.ts';
// Done once in every runtime context to init transport layer
initPegasusTransport();
registerRPCService(
'MathService',
new MathService(),
);
injected.ts
// Important to import type only as we don't want to cause any errors by injecting
// code that expects web extension runtime to be loaded on target webpag
import type {IMathService} from './MathService.ts';
import {getRPCService} from '@webext-pegasus/rpc';
import {initPegasusTransport} from '@webext-pegasus/transport/window';
// Done once in every runtime context to init transport layer
initPegasusTransport();
const mathService = getRPCService<IMathService>(
// Same ID that was used for registration
// We may have multiple instances of the same service executed independently
'MathService',
// Where sevice was registered
'background',
);
// Note that now mathService.fibonacci() returns Promise
mathService.fibonacci(10).then(console.log);
// Output: 89
Functional services
This library also allows you to define RPC service as a function (as showcased in example).
getTestHelloService.ts
import {PegasusRPCMessage} from '@webext-pegasus/rpc';
export type ITestHelloService = typeof getTestHelloService;
export function getTestHelloService(
_message: PegasusRPCMessage,
name: string,
): string {
return `Warmest hello for ${name} from the service!`;
}
Which can be later called (don't forget to register it first via registerRPCService
) in the following way:
const getTestHelloService = getRPCService<ITestHelloService>(
'getTestHello',
'background',
);
getTestHelloService('Mike').then(console.log);
// Will print:
// Warmest hello for Mike from the service!
PegasusRPCMessage
Message information provided as a first parameter to every public method of Pegasus RPC service serves a purpose of identifying caller identity and providing relevant response.
This is useful for example to create a SelfIDService
that allows to retrieve it's tabId
and frameId
for content script, window script or popup.
getSelfIDService.ts
import {PegasusRPCMessage} from '@webext-pegasus/rpc';
import browser from 'webextension-polyfill';
export type ISelfIDService = typeof getSelfIDService;
export async function getSelfIDService(message: PegasusRPCMessage): Promise<{
tabId: number;
frameId?: number;
}> {
let tabId: number | undefined = message.sender.tabId;
if (message.sender.context === 'popup') {
tabId = (await browser.tabs.query({active: true, currentWindow: true}))[0]
.id;
}
if (tabId === undefined) {
throw new Error(`Could not get tab ID for message: ${message.toString()}`);
}
return {frameId: message.sender.frameId, tabId};
}