ryst

Ryst

Ryst is lightweight library for promise-based http requests in node-js, sort of a chimera-like mix between node-js' built-in https library, and modern promise-based code.

The example code in this README will be written in typescript.

Making requests

The most important and fundamental function in ryst is request(). As the name entails, it will send an http-request to a server. By default, this will be a GET-Request.

This method takes three arguments:

• url, which can either be a URL instance or a string
• options, which will be covered in more detail shortly
• cb, a callback function which will be passed an IncomingMessage instance, just like in node's built-in package.

The method will return a ryst.Request, whose properties will also be covered later, but which contains all properties of the http.ClientRequest-class from the http package.

Request Options

The options argument is very similar to the options that can be passed as the first parameter of https.request(); in fact, it contains all of it's properties, except the following, which can instead be encoded into a URL-object passed as the first parameter:

• host
• hostname
• path
• port
• protocol
• auth

In addition, it contains the following new properties:

• data, which can be passed a string, a buffer, or an object that will be encoded as JSON; this will be sent as the request's content.
• encoding, the text encoding of the message's content; by default utf-8.
• dataWriteCallback, a callback that is called when data is written to the request, being given an error as an argument if one occured. The same that would be passed to http.ClientRequest.prototype.write.

Helper Functions

For convenience, ryst supports the following functions, which are identical to ryst.request(), except that the method is predetermined and can't be set in the options:

• ryst.get(), which sends a get request
• ryst.post(), which sends a post request
• ryst.head(), which sends a head request

Sending a request

Creating a post request with this method might look something like this:

import * as ryst from "ryst";

const req = ryst.post("https://some.server.com", {
	headers: {
		"Content-Type": "application/json"
	},
	data: {
		property: "value",
		anotherProperty: 2
	}
});

The Request Object

The ryst.Request object can be handled in two ways: either using Promises, or almost exactly like a http.ClientRequest. You can also use a mixture of both.

Using Promises

When using ryst.Request using Promises, the ryst.Request object itself can be treated like a promise returning a ryst.Response object.

With this method, logging the html of the google homepage might look something like this:

import * as ryst from "ryst";

// Using normal promise functions
const req = ryst.get("https://www.google.com");
req.then(res => console.log(res.data));

// using async/await (only within asynchronous functions):
const res = await ryst.get("https://www.google.com");
console.log(res.data);

Like A ClientRequest

When using ryst.Request like a http.ClientRequest, response data is obtained by using event listeners. For conveniences sake, ryst.Request emits an event that http.ClientRequest doesn't, which is the data event. It will be emitted exactly once when the response data has been entirely recieved, and passed a ryst.Response object as a parameter, which will be explained in detail shortly.

It is also possible to write headers and data to the request using setHeader() and write() respectively, as well as other such methods inherited from http.ClientRequest.

Note that using this method, it is necessary to close the request manually using the end() method.

With this method, logging the html of the google homepage might look something like this:

import * as ryst from "ryst";

const req = ryst.get("https://www.google.com");
req.on("data", res => console.log(res.data))
req.end();

Mixing the two methods

It is of course possible to mix the two methods, for example using write() to write content to the request or setHeader() to write headers, and then using await to get the response. You can also use event listeners on requests while also treating them as a promise. The only caveat here is that awaiting a request or calling then() on it has the same effect of calling end(); at that moment the request will be sent and it is no longer possible to alter it.

As an example, you could set request headers this way instead of using the options parameter:

const req = ryst.get("https://www.google.com");
req.setHeader("Accept", "text/html");
const res = await req;
console.log(res.data);

The Response Object

The response object contains two properties; message, which is an instance of IncomingMessage, containing meta data for the response such as headers and the status code, and data, which is the response data. It also has the json() method, which automatically parses the data as json and returns it, if the data is in fact a string. This method will throw an error if the data is a string but not of valid json format; if the data is not a string it will simply return null.