Node.js JavaScript Basic Get Request - javascript

Just installed node.js, and I'm having trouble sending basic get requests. I used to run things in chrome/firefox's console but wanted to branch out. What I am trying to do (as a test) is send a get request to a webpage, and have it print out some text on it.
In chrome's console, I would do something like this:
$.get("http://stackoverflow.com/questions/1801160/can-i-use-jquery-with-node-js", function(data) {
console.log($(data).find(".question-hyperlink")[0].innerHTML);
});
In node.js, how would I do that? I've tried requiring a few things and gone off a few examples but none of them worked.
Later on, I'll also need to add parameters to get and post requests, so if that involves something different, could you show how to send the request with the parameters {"dog":"bark"}? And say it returned the JSON {"cat":"meow"}, how would I read/get that?

You can install the request module with:
npm install request
And, then do this in your node.js code:
const request = require('request');
request.get("http://stackoverflow.com/questions/1801160/can-i-use-jquery-with-node-js", function(err, response, body) {
if (err) {
// deal with error here
} else {
// you can access the body parameter here to see the HTML
console.log(body);
}
});
The request module supports all sorts of optional parameters you can specify as part of your request for everything from custom headers to authentication to query parameters. You can see how to do all those things in the doc.
If you want to parse and search the HTML with a DOM like interface, you can use the cheerio module.
npm install request
npm install cheerio
And, then use this code:
const request = require('request');
const cheerio = require('cheerio');
request.get("http://stackoverflow.com/questions/1801160/can-i-use-jquery-with-node-js", function(err, response, body) {
if (err) {
// deal with error here
} else {
// you can access the body parameter here to see the HTML
let $ = cheerio.load(body);
console.log($.find(".question-hyperlink").html());
}
});

Related

Route that is executed within another route in Node.js is not being executed

Good Evening,
I have a function that contains a route that is a call to the Auth0 API and contains the updated data that was sent from the client. The function runs, but the app.patch() does not seem to run and I am not sure what I am missing.
function updateUser(val) {
app.patch(`https://${process.env.AUTH0_BASE_URL}/api/v2/users/${val.id}`,(res) => {
console.log(val);
res.header('Authorization: Bearer <insert token>)
res.json(val);
})
app.post('/updateuser', (req, ) => {
const val = req.body;
updateUser(val);
})
app.patch() does NOT send an outgoing request to another server. Instead, it registers a listener for incoming PATCH requests. It does not appear from your comments that that is what you want to do.
To send a PATCH request to another server, you need to use a library that is designed for sending http requests. There's a low level library built into the nodejs http module which you could use an http.request() to construct a PATCH request with, but it's generally a lot easier to use a higher level library such as any of them listed here.
My favorite in that list is the got() library, but many in that list are popular and used widely.
Using the got() library, you would send a PATCH request like this:
const got = require('got');
const options = {
headers: {Authorization: `Bearer ${someToken}`},
body: someData
};
const url = `https://${process.env.AUTH0_BASE_URL}/api/v2/users/${val.id}`;
got.patch(url, options).then(result => {
console.log(result);
}).catch(err => {
console.log(err);
});
Note: The PATCH request needs body data (the same that a POST needs body data)

Invoking Rest API from Lambda (JS; Web Console)

_
MY CHALLENGE:
I would like to access a third party Rest API from within my Lambda function. (e.g."http://www.mocky.io/v2/5c62a4523000004a00019907").
This will provide back a JSON file which I will then use for data extraction
_
MY CURRENT CODE:
var http = require('http');
exports.handler = function(event, context, callback) {
console.log('start request to Mocky');
http.get('http://www.mocky.io/v2/5c62a4523000004a00019907', function(res) {
console.log(res);
})
.on('error', function(e) {
console.log("Got error: " + e.message);
});
};
This does not throw an error but also does not seem to provide back the JSON
_
MY OPEN QUESTIONS:
1) How can I extract the JSON so that I can work on it
2) I will probably need to also send through an Authentification in the request header (Bearer) in the future. Will this also be possible with this method?
The problem is likely that your lambda function is exiting before logging the response.
We use Authorization headers all the time to call our lambdas. The issue of if you can use one to call the third party API is up to them, not you, so check the documentation.
Since your HTTP call is executed asynchronously, the execution of the lambda continues while that call is being resolved. Since there are no more commands in the lambda, it exits before your response returns and can be logged.
EDIT: the http.get module is difficult to use cleanly with async/await. I usually use superagent, axios, or request for that reason, or even node-fetch. I'll use request in my answer. If you must use the native module, then see EG this answer. Otherwise, npm install request request-promise and use my answer below.
The scheme that many people use these days for this kind of call uses async/await, for example (Requires Node 8+):
var request = require('request-promise')
exports.handler = async function(event, context, callback) {
console.log('start request to Mocky');
try {
const res = await request.get('http://www.mocky.io/v2/5c62a4523000004a00019907')
console.log(res)
callback(null, { statusCode: 200, body: JSON.stringify(res) })
}
catch(err) {
console.error(err.message)
callback('Got error ' + err.message)
}
};
The async/await version is much easier to follow IMO.
Everything inside an async function that is marked with await with be resolved before the execution continues. There are lots of articles about this around, try this one.
There are a lot of guys having an equal problem already solved... Look at that
or that

node.js internal message server

I am pretty new to node.js. I am working on an app able to display NFC content on a webpage. I am using nfc-pcsp package (https://github.com/pokusew/nfc-pcsc), I can easily read data on server side. Now I just would like to display the data in the webpage, but I am stuck on the logic. Here is a part of my server code:
// ### launch server for client
var http = require('http');
var html = require('fs').readFileSync(__dirname+'/custom.html');
var server = require('http').createServer(function(req, res){
res.end(html);
});
server.listen(3000, '127.0.0.1');
console.log('Server running at http://127.0.0.1:3000/');
//######
//#launch NFC routine ######
const nfc = new NFC(); // const nfc = new NFC(minilogger); // optionally you can pass logger to see internal debug logs
let readers = [];
nfc.on('reader', async reader => {
pretty.info(`device attached`, { reader: reader.name });
// the event is correctly displayed in the console. How to update html here?
readers.push(reader);
nfc.on('error', err => {
pretty.error(`an error occurred`, err);
});
It seems to me that I need a res object to update the html page, but as I do not get any request from client, how do I update the page just based on the callback from NFC module reader? Hope my question is clear.
Thanks,
Matt
I suggest you to use the express API
command with npm CLI : npm install --save express at your root project folder in your terminal
Then, you will be able to create a route in Get, Post, Put or Delete.
Next, In your client side you will be able to call this route by a get, post or whatever with a promise, ajax request whatever you want :)
Just understand that in order to receive or send data to your server, you need an url and with Express, you can create your own url.
https://www.npmjs.com/package/express
Don't hesitate to have a look on this API, and i'm pretty sure you will find the answer to your question on your own :)

Meteor: what is the final Location/URL after following redirects?

Meteor's HTTP package is a wrapper around mikeal's request, and it supports the followRedirects option. But how can one find out what the final URL is, after the 3xx redirect responses have been followed (and the request didn't fail because of lack of a cookie jar)?
With request, the final URL is in response.request.href. But with Meteor... ?
Here's the Meteor code:
if (Meteor.isServer) {
Meteor.startup(function () {
var url = 'http://google.com';
var result = HTTP.call("HEAD", url, {
followRedirects: true
});
console.log(result); // nothing here hints at the final URL
});
}
I've created a package that does this - http-more.
Turns out Meteor doesn't pass back the request object within the response, and given the history of rejected PRs concerning enhancements to the HTTP package, I've just implemented that option separately.

Simple API Calls with Node.js and Express

I'm just getting started with Node, APIs, and web applications.
I understand the basic workings of Node.js and Express, but now I want to start making calls to other service's APIs and to do stuff with their data.
Can you outline basic HTTP requests and how to grab/parse the responses in Node? I'm also interested in adding specific headers to my request (initially I'm using the http://www.getharvest.com API to crunch my time sheet data).
P.S. This seems simple, but a lot of searching didn't turn up anything that answered my question. If this is dupe, let me know and I'll delete.
Thanks!
You cannot fetch stuff with Express, you should use Mikeal's request library for that specific purpose.
Installation: npm install request
The API for that library is very simple:
const request = require('request');
request('http://www.google.com', function (error, response, body) {
if (!error && response.statusCode == 200) {
console.log(body) // Print the google web page.
}
})
Edit: You're better of using this library instead of the http default one because it has a much nicer API and some more advanced features (it even supports cookies).
UPDATE: request has been deprecated, but there are some nice alternatives still such as 'got' or 'superagent' (look them up on npm).
You can use the http client:
var http = require('http');
var client = http.createClient(3000, 'localhost');
var request = client.request('PUT', '/users/1');
request.write("stuff");
request.end();
request.on("response", function (response) {
// handle the response
});
Also, you can set headers as described in the api documentation:
client.request(method='GET', path, [request_headers])
Required install two package.
npm install ejs
npm install request
server.js
var request = require('request');
app.get('/users', function(req, res) {
request('https://jsonplaceholder.typicode.com/users', function(error, response, body) {
res.json(body)
});
});
index.ejs
$.ajax({
type: "GET",
url: 'http://127.0.0.1:3000/posts',
dataType: "json",
success: function(res) {
var res_data = JSON.parse(res);
console.log(res_data);
}
});
Output

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