mirror of https://github.com/status-im/EIPs.git
388 lines
12 KiB
Markdown
388 lines
12 KiB
Markdown
---
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eip: 1193
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title: Ethereum Provider JavaScript API
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author: Fabian Vogelsteller (@frozeman), Ryan Ghods (@ryanio), Marc Garreau (@marcgarreau), Victor Maia (@MaiaVictor)
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discussions-to: https://ethereum-magicians.org/t/eip-1193-ethereum-provider-javascript-api/640
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status: Draft
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type: Standards Track
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category: Interface
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created: 2018-06-30
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requires: 155, 695, 1102, 1474
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---
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## Summary
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This EIP formalizes an Ethereum Provider JavaScript API for consistency across clients and applications. The provider is designed to be minimal and is intended to be available on `window.ethereum` for cross environment compatibility.
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## API
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### Send
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Ethereum API methods can be sent and received:
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```js
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ethereum.send(method: String, params?: Array<any>): Promise<any>;
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```
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Promise resolves with `result` or rejects with `Error`.
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See the [available methods](https://github.com/ethereum/wiki/wiki/JSON-RPC#json-rpc-methods).
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### Events
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Events are emitted using [EventEmitter](https://nodejs.org/api/events.html).
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#### notification
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All subscriptions from the node emit on notification. Attach listeners with:
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```js
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ethereum.on('notification', listener: (result: any) => void): this;
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```
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To create a subscription, call `ethereum.send('eth_subscribe', [])` or `ethereum.send('shh_subscribe', [])`.
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See the [eth subscription methods](https://github.com/ethereum/go-ethereum/wiki/RPC-PUB-SUB#supported-subscriptions) and [shh subscription methods](https://github.com/ethereum/go-ethereum/wiki/Whisper-v6-RPC-API#shh_subscribe).
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#### connect
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The provider emits `connect` on connect to a network.
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```js
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ethereum.on('connect', listener: () => void): this;
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```
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You can detect which network by sending `net_version`:
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```js
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const network = await ethereum.send('net_version');
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> '1'
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```
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#### close
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The provider emits `close` on disconnect from a network.
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```js
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ethereum.on('close', listener: (code: Number, reason: String) => void): this;
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```
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The event emits with `code` and `reason`. The code follows the table of [`CloseEvent` status codes](https://developer.mozilla.org/en-US/docs/Web/API/CloseEvent#Status_codes).
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#### chainChanged
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The provider emits `chainChanged` on connect to a new chain.
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```js
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ethereum.on('chainChanged', listener: (chainId: String) => void): this;
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```
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The event emits with `chainId`, the new chain returned from `eth_chainId`.
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#### networkChanged
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The provider emits `networkChanged` on connect to a new network.
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```js
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ethereum.on('networkChanged', listener: (networkId: String) => void): this;
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```
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The event emits with `networkId`, the new network returned from `net_version`.
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#### accountsChanged
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The provider emits `accountsChanged` if the accounts returned from the provider (`eth_accounts`) changes.
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```js
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ethereum.on('accountsChanged', listener: (accounts: Array<String>) => void): this;
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```
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The event emits with `accounts`, an array of the accounts' addresses.
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## Examples
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```js
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const ethereum = window.ethereum;
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// A) Set provider in web3.js
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var web3 = new Web3(ethereum);
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// web3.eth.getBlock('latest', true).then(...)
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// B) Use provider object directly
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// Example 1: Log last block
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ethereum
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.send('eth_getBlockByNumber', ['latest', 'true'])
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.then(block => {
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console.log(`Block ${block.number}:`, block);
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})
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.catch(error => {
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console.error(
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`Error fetching last block: ${error.message}.
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Code: ${error.code}. Data: ${error.data}`
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);
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});
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// Example 2: Log available accounts
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ethereum
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.send('eth_accounts')
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.then(accounts => {
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console.log(`Accounts:\n${accounts.join('\n')}`);
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})
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.catch(error => {
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console.error(
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`Error fetching accounts: ${error.message}.
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Code: ${error.code}. Data: ${error.data}`
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);
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});
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// Example 3: Log new blocks
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let subId;
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ethereum
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.send('eth_subscribe', ['newHeads'])
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.then(subscriptionId => {
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subId = subscriptionId;
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ethereum.on('notification', result => {
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if (result.subscription === subscriptionId) {
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if (result.result instanceof Error) {
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const error = result.result;
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console.error(
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`Error from newHeads subscription: ${error.message}.
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Code: ${error.code}. Data: ${error.data}`
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);
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} else {
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const block = result.result;
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console.log(`New block ${block.number}:`, block);
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}
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}
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});
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})
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.catch(error => {
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console.error(
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`Error making newHeads subscription: ${error.message}.
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Code: ${error.code}. Data: ${error.data}`
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);
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});
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// Example 4: Log when accounts change
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const logAccounts = accounts => {
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console.log(`Accounts:\n${accounts.join('\n')}`);
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};
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ethereum.on('accountsChanged', logAccounts);
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// to unsubscribe
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ethereum.removeListener('accountsChanged', logAccounts);
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// Example 5: Log if connection ends
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ethereum.on('close', (code, reason) => {
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console.log(`Ethereum provider connection closed: ${reason}. Code: ${code}`);
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});
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```
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## Specification
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### Errors
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If the Ethereum Provider request returns an error property then the Promise **MUST** reject with an Error object containing the `error.message` as the Error message, `error.code` as a code property on the error and `error.data` as a data property on the error.
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If an error occurs during processing, such as an HTTP error or internal parsing error, then the Promise **MUST** reject with an `Error` object.
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If the request requires an account that is not yet authenticated, the Promise **MUST** reject with Error code 4100.
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### Events
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The provider **SHOULD** extend from `EventEmitter` to provide dapps flexibility in listening to events. In place of full `EventEmitter` functionality, the provider **MAY** provide as many methods as it can reasonably provide, but **MUST** provide at least `on`, `emit`, and `removeListener`.
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#### notification
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All subscriptions received from the node **MUST** emit the `subscription` property with the subscription ID and a `results` property.
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#### connect
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If the network connects, the Ethereum Provider **MUST** emit an event named `connect`.
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#### close
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If the network connection closes, the Ethereum Provider **MUST** emit an event named `close` with args `code: Number, reason: String` following the [status codes for `CloseEvent`](https://developer.mozilla.org/en-US/docs/Web/API/CloseEvent#Status_codes).
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#### chainChanged
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If the chain the provider is connected to changes, the provider **MUST** emit an event named `chainChanged` with args `chainId: String` containing the ID of the new chain (using the Ethereum JSON-RPC call `eth_chainId`).
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#### networkChanged
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If the network the provider is connected to changes, the provider **MUST** emit an event named `networkChanged` with args `networkId: String` containing the ID of the new network (using the Ethereum JSON-RPC call `net_version`).
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#### accountsChanged
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If the accounts connected to the Ethereum Provider change at any time, the Ethereum Provider **MUST** send an event with the name `accountsChanged` with args `accounts: Array<String>` containing the accounts' addresses.
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### web3.js Backwards Compatibility
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If the implementing Ethereum Provider would like to be compatible with `web3.js` prior to `1.0.0-beta38`, it **MUST** provide the method: `sendAsync(payload: Object, callback: (error: any, result: any) => void): void`.
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### Error object and codes
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If an Error object is returned, it **MUST** contain a human readable string message describing the error and **SHOULD** populate the `code` and `data` properties on the error object with additional error details.
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Appropriate error codes **SHOULD** follow the table of [`CloseEvent` status codes](https://developer.mozilla.org/en-US/docs/Web/API/CloseEvent#Status_codes), along with the following table:
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| Status code | Name | Description |
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| ----------- | ---------------------------- | --------------------------------------------------------------------- |
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| 4001 | User Denied Request Accounts | User denied authorizing any accounts for the dapp. |
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| 4010 | User Denied Create Account | User denied creating a new account. |
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| 4100 | Unauthorized | The requested account has not been authorized by the user. |
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| 4200 | Unsupported Method | The requested method is not supported by the given Ethereum Provider. |
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## Sample Class Implementation
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```js
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class EthereumProvider extends EventEmitter {
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constructor() {
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// Call super for `this` to be defined
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super();
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// Init storage
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this._nextJsonrpcId = 0;
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this._promises = {};
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// Fire the connect
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this._connect();
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// Listen for jsonrpc responses
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window.addEventListener('message', this._handleJsonrpcMessage.bind(this));
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}
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/* Methods */
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send(method, params = []) {
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if (!method || typeof method !== 'string') {
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return new Error('Method is not a valid string.');
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}
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if (!(params instanceof Array)) {
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return new Error('Params is not a valid array.');
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}
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const id = this._nextJsonrpcId++;
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const jsonrpc = '2.0';
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const payload = { jsonrpc, id, method, params };
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const promise = new Promise((resolve, reject) => {
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this._promises[payload.id] = { resolve, reject };
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});
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// Send jsonrpc request to Mist
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window.postMessage(
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{ type: 'mistAPI_ethereum_provider_write', message: payload },
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targetOrigin
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);
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return promise;
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}
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/* Internal methods */
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_handleJsonrpcMessage(event) {
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// Return if no data to parse
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if (!event || !event.data) {
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return;
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}
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let data;
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try {
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data = JSON.parse(event.data);
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} catch (error) {
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// Return if we can't parse a valid object
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return;
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}
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// Return if not a jsonrpc response
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if (!data || !data.message || !data.message.jsonrpc) {
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return;
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}
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const message = data.message;
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const { id, method, error, result } = message;
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if (typeof id !== 'undefined') {
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const promise = this._promises[id];
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if (promise) {
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// Handle pending promise
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if (data.type === 'error') {
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promise.reject(message);
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} else if (message.error) {
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promise.reject(error);
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} else {
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promise.resolve(result);
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}
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delete this._promises[id];
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}
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} else {
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if (method && method.indexOf('_subscription') > -1) {
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// Emit subscription notification
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this._emitNotification(message.params);
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}
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}
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}
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/* Connection handling */
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_connect() {
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// Send to Mist
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window.postMessage(
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{ type: 'mistAPI_ethereum_provider_connect' },
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targetOrigin
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);
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// Reconnect on close
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this.once('close', this._connect.bind(this));
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}
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/* Events */
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_emitNotification(result) {
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this.emit('notification', result);
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}
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_emitConnect() {
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this.emit('connect');
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}
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_emitClose(code, reason) {
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this.emit('close', code, reason);
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}
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_emitNetworkChanged(networkId) {
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this.emit('networkChanged', networkId);
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}
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_emitAccountsChanged(accounts) {
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this.emit('accountsChanged', accounts);
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}
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/* web3.js Provider Backwards Compatibility */
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sendAsync(payload, callback) {
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return this.send(payload.method, payload.params)
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.then(result => {
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const response = payload;
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response.result = result;
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callback(null, response);
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})
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.catch(error => {
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callback(error, null);
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// eslint-disable-next-line no-console
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console.error(
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`Error from EthereumProvider sendAsync ${payload}: ${error}`
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);
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});
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}
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}
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```
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## Copyright
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Copyright and related rights waived via [CC0](https://creativecommons.org/publicdomain/zero/1.0/).
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