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@krisselden
Last active February 1, 2016 00:13
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Event Promise
import { EventEmitter } from "events";
export default function eventPromise<T>(emitter: EventEmitter, resolveEvent: string, rejectEvent: string): Promise<T> {
return new Promise<T>((resolve, reject) => {
let resolveHandler = (evt) => {
resolve(evt);
emitter.removeListener(resolveEvent, resolveHandler);
emitter.removeListener(rejectEvent, rejectHandler);
}
let rejectHandler = (evt) => {
reject(evt);
emitter.removeListener(resolveEvent, resolveHandler);
emitter.removeListener(rejectEvent, rejectHandler);
}
emitter.on(resolveEvent, resolveHandler);
emitter.on(rejectEvent, rejectHandler);
});
}
import * as http from "http";
import * as WebSocket from "ws";
import eventPromise from "./event-promise";
export async function openWebSocket(url: string): Promise<WebSocket> {
let ws = new WebSocket(url);
return eventPromise(ws, "open", "error").then(() => ws);
}
export async function getResponse(options: any): Promise<http.IncomingMessage> {
let request = http.get(options);
return eventPromise<http.IncomingMessage>(request, "response", "error");
}
export async function readResponseBody(response: http.IncomingMessage): Promise<string> {
let body = "";
response.setEncoding("utf8");
response.on("data", (chunk) => {
body += chunk;
});
return eventPromise(response, "end", "error").then(() => body);
}
class ResponseError extends Error {
status: number;
constructor(message: string, status: number) {
super(message);
this.status = status;
}
}
export async function get(options: any): Promise<string> {
let response = await getResponse(options);
let status = response.statusCode;
let body = await readResponseBody(response);
if (status !== 200) {
throw new ResponseError(body, status);
}
return body;
}
export async function getJSON<T>(options: any): Promise<T> {
let body = await get(options);
return JSON.parse(body);
}
@krisselden
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An utility function for creating a promise of an event with example code that it cleans up.

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