Handles JSON-RPC methods for Ethereum

eth.service.ts

import { Injectable } from '@angular/core';
import { Provider } from 'provider.service.ts';
import BN from 'bn';

@Injectable({ providedIn : 'root' })
export class Eth {

  constructor(private provider: Provider) {}

  /** Transform a value into hex or decimal string for example */
  private toBN(value: string, from: number, to: number) {
    return new BN(value, from).toString(to);
  }

  /** Get the current block number */
  public getBlockNumber(): Observable<string> {
    return this.provider
      .rpc<string>('eth_blockNumber')
      .pipe(map(block => this.toBN(block, 16, 10)));
  }
  
  /** Get the balance of an account at a specific block number, default is the latest */
  public getBalance(account: string, block: number | 'latest' = 'latest'): Observable<string> {
    if (typeof block === 'number') { block = this.toBN(block, 10, 16); }
    return this.provider
      .rpc<string>('eth_getBalance', [account, block])
      .pipe(map(amount => this.toBN(amount)));
  }

}