NodeJS : How to have multiple methods for post - javascript

i am trying to make an iteractive form using nodejs.
Here is my web page
<!DOCTYPE html>
<html>
<script>
$('#ping-button').click(function() {
$.ajax({
type: 'POST',
url: 'http://localhost:3000/process_test'
});
});
</script>
<body>
<form action="http://127.0.0.1:3000/process_get" method="GET">
First Name: <input type="text" name="first_name"> <br>
Last Name: <input type="text" name="last_name">
<input type="submit" value="Submit">
</form>
<br>
<form action="http://127.0.0.1:3000/process_post" method="POST">
Team: <input type="text" name="team"> <br>
Player: <input type="text" name="player">
<input type="submit" value="Submit">
<br><br>
<button id='ping-button'>Ping</button>
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.3/jquery.min.js"></script>
</form>
</body>
</html>
and here is my app.js
var express = require('express');
var app = express();
var bodyParser = require('body-parser');
// Create application/x-www-form-urlencoded parser
var urlencodedParser = bodyParser.urlencoded({ extended: false })
app.use(express.static('test'));
app.get('/index.html', function (req, res) {
res.sendFile( __dirname + "/" + "index.html" );
})
app.get('/process_get', function (req, res) {
// Prepare output in JSON format
response = {
first_name:req.query.first_name,
last_name:req.query.last_name
};
console.log(response);
res.end(JSON.stringify(response));
})
app.post('/process_test', urlencodedParser, function (req, res) {
console.log("Ping");
res.end(JSON.stringify("Ping"));
})
app.post('/process_post', urlencodedParser, function (req, res) {
// Prepare output in JSON format
response = {
team:req.body.team,
player:req.body.player
};
console.log(response);
res.end(JSON.stringify(response));
})
var server = app.listen(3000, function () {
var host = server.address().address
var port = server.address().port
console.log("Example app listening at http://%s:%s", host, port)
})
so i have two forms and a button. The first form is tied to the process_get method, the second form is tied to the process_post method and the button is tied to the process_test method.
both of the forms give expected results. When i click the button, it goes to the process_post method instead of the process_test
why does this happen?

The reason the Ping button submits the form to /process_post is because it is inside the form, and the click handler is not set due to errors.
If you open the console in your browser you will see Uncaught ReferenceError: $ is not defined. This is because you're using $ in your code, but you include jQuery much later in the page. This you can fix by loading jQuery prior to your script tag.
Once that is done you will notice that the button still does not work. This is because the script inside head is executed before the rest of the document is done, ie. the body contents is not there yet, and $('#ping_button') will find nothing. This you fix by wrapping you code inside $(document).ready(function() { // code here }); so it is executed once the whole page is loaded.
Still, clicking the button will send you to /process_post because the click event is not stopped in your click handler. Return false or use e.preventDefault() to disable the browser default action.
All this combined the head section (that was missing) will become
<!DOCTYPE html>
<html>
<head>
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.3/jquery.min.js"></script>
<script>
$(document).ready(function() {
$('#ping-button').click(function(e) {
e.preventDefault();
$.ajax({
type: 'POST',
url: 'http://localhost:3000/process_test'
});
return false;
});
});
</script>
</head>
<body>
<!-- Rest of your page -->
</body>
</html>

Related

Call an API-endpoint and print a message on client side by clicking a button

I have a very simple assignment for my school, but I just can't figure out how to solve it.
I need to create an endpoint for an API in Node.JS that responds to a GET request - so when I click the button in my HTML file, it should call my API endpoint and print the message "Hello World" and the number of times it has been called in an alert box.
UPDATED, UPDATED:
client/index.html
<html>
<head></head>
</body>
<!--
When clicking this button, an alert needs to show up
displaying a GET request from the server.js file with
the text "Hello World" a long with a number increasing
for each time, the call has been made
-->
<button id="myBtn" type="button" onclick="alertCount()">Send</button>
<script src="js/javascript.js"></script>
</body>
</html>
client/javascript.js
function alertCount() {
fetch("http://localhost:3000").then(res => {
console.log("log");
return res.text()
}).then(text => {
alert(text)
})
};
server/server.js
const express = require('express');
const app = express();
const port = 3000;
let counter = 0;
app.use(express.static('client'));
app.get('/', (req, res) => {
res.send('"Hello World!" has been called ' + counter + ' time(s).');
++counter;
});
app.listen(port, () => console.log("Listening..."));
You need to add a function in the onclick handler of the button. See an example here
// javascript.js
function myFunction() {
fetch("https://5f7203e364a3720016e61337.mockapi.io/text").then(res => {
return res.text()
}).then(text => {
alert(text)
})
}
<!-- index.html -->
<button onclick="myFunction()">Click me</button>
<p id="demo"></p>
<script src="javascript.js"></script>
EDIT: updated the script, all you need to do is replace the url inside the fetch()

Node how to manipulate HTML DOM - document not found error

I have a Node server that serves various different HTML pages. In one of the pages there is a form. When the form is clicked, an endpoint in the node server.js file consumes the form data. The same HTML page contains a element whose text content i'd like to modify when the form is submitted. I've seen various tutorials online showcasing how to use document.getElementById('predictionText').innerHTML = prediction; to set the value of the text dynamically using inline javascript. How do I achieve this using Node and external js?
Below is my code:
<!DOCTYPE html>
<html>
<head>
<link rel="stylesheet" type="text/css" href="css/styles.css">
</head>
<body class="bodyContent">
<p>This is the predictor page -- it will hold a form for the user to input relevant data to.</p>
<section class="active" id="navigationBarSection">
<ul>
<li>Home</li>
<li>Predictor</li>
<li>How it Works</li>
<li>About Us</li>
</ul>
</section>
<section id="predictorUserInputSection">
<form action="/post_data_to_predictor_algorithm" method="POST" id="attributeInputForm">
<input class="textInput" required name="averageAreaIncome" placeholder="Average Area Income" />
<input class="textInput" required name="averageAreaNumberOfRooms" placeholder="Average Area Number of Rooms" />
<input class="textInput" required name="averageAreaHouseAge" placeholder="Average Area House Age" />
<input class="textInput" required name="averageAreaNumberOfBedrooms" placeholder="Average Area Number of Bedrooms"/>
<input class="textInput" required name="areaPopulation" placeholder="Area Population"/>
<button id="submitButton">Submit</button>
</form>
</section>
<section id="predictionResultsSection">
<p id="predictionText"><font size="6">here </p>
</section>
<script src="server.js"></script>
</body>
</html>
The node server that should update the text:
//jshint esversion:8
//adding all required dependencies/packages
const express = require('express');
const path = require('path');
const fs = require("fs");
const bodyParser = require('body-parser'); //for parsing post requests
const request = require('request') //for making HTTP requests
//specifies that this app will be using express.
const app = express();
//middleware for processing POST requests a bit easier.
app.use(bodyParser.urlencoded({extended: false}));
//static AWS EC2 instance server port. Edit with caution.
const serverPort = 5001;
const FLASK_SERVER_LOCAL_ENDPOINT = "http://localhost:5000/predictPrice";
//Allow the use of static files in project directory
app.use('/js', express.static(__dirname + '/js'));
app.use('/html', express.static(__dirname + '/html'));
app.use('/css', express.static(__dirname + '/css'));
app.use('/node_modules', express.static(__dirname + '/node_modules'));
app.use('/resources', express.static(__dirname + '/resources'));
const XMLHttpRequest = require("xmlhttprequest").XMLHttpRequest;
//Handle all root requests.
app.get("/", function(req, res) {
res.sendFile(path.resolve("index.html"));
});
app.get("/index", function(req, res) {
res.sendFile(path.resolve("index.html"));
});
app.get("/predictor", function(req, res) {
res.sendFile(path.resolve("html/predictor.html"));
});
app.get("/how_it_works", function(req, res) {
res.sendFile(path.resolve("html/how_it_works.html"));
});
app.get("/about_us", function(req, res) {
res.sendFile(path.resolve("html/about_us.html"))
});
//HERE IS THE PROBLEM
app.post("/post_data_to_predictor_algorithm", (req, res) => {
//update prediction label in the UI:
console.log("Updating label!");
document.getElementById('predictionText').innerHTML = "received user response!";
});
When running the server, I get the following error when submitting the form:
ReferenceError: document is not defined
at app.post (/Users/vismarkjuarez/Documents/Github/RealEstatePriceEstimator/server.js:90:3)
at Layer.handle [as handle_request] (/Users/vismarkjuarez/Documents/Github/RealEstatePriceEstimator/node_modules/express/lib/router/layer.js:95:5)
at next (/Users/vismarkjuarez/Documents/Github/RealEstatePriceEstimator/node_modules/express/lib/router/route.js:137:13)
at Route.dispatch (/Users/vismarkjuarez/Documents/Github/RealEstatePriceEstimator/node_modules/express/lib/router/route.js:112:3)
at Layer.handle [as handle_request] (/Users/vismarkjuarez/Documents/Github/RealEstatePriceEstimator/node_modules/express/lib/router/layer.js:95:5)
at /Users/vismarkjuarez/Documents/Github/RealEstatePriceEstimator/node_modules/express/lib/router/index.js:281:22
at Function.process_params (/Users/vismarkjuarez/Documents/Github/RealEstatePriceEstimator/node_modules/express/lib/router/index.js:335:12)
at next (/Users/vismarkjuarez/Documents/Github/RealEstatePriceEstimator/node_modules/express/lib/router/index.js:275:10)
at /Users/vismarkjuarez/Documents/Github/RealEstatePriceEstimator/node_modules/body-parser/lib/read.js:130:5
at invokeCallback (/Users/vismarkjuarez/Documents/Github/RealEstatePriceEstimator/node_modules/raw-body/index.js:224:16)
if you want update DOM element in the same page of form, you have to build a dynamic form cause the standard one with action="/destination" will send you to a new page, or rebuild an existing one where you cant write on the document cause node dont know DOM. You need Jquery or work directly with xhr. For instance:
// Build a single field dynamic Form:
<div id="myForm">
<input type="text" id="textA"></input>
<button type="submit" onclick="getElements()"> Submit </button>
</div>
// The element that need be updated.
<section id="predictionResultsSection">
<p id="predictionText"><font size="6">here </p>
</section>
// Get the "form" field value.
function getElements() {
var tA = document.getElementById("textA");
formSubmit(tA.value)
}
// Do the request
function formSubmit(sendData) {
var xhttp = new XMLHttpRequest();
xhttp.open("POST", "http://localhost/post_data_to_predictor_algorithm");
xhttp.send(sendData);
// Receive the response from server on this.responseText var
xhttp.onreadystatechange = function () {
if (this.readyState == 4 && this.status == 200) {
document.getElementById('predictionText').innerHTML = this.responseText;
}
};
}
// Server side
app.post("/post_data_to_predictor_algorithm", (req, res) => {
//do your logic and send the response
res.send(yourResponse) // the onreadystatechange will hadle this on responseText
});

How to put HTML text-box form input into Express Route Paramater

I am trying to create a way for users to search through my mongo database via an endpoint like this:
app.get('/search/:input', function(req, res){
console.log(`get request to: /members/${req.params.input}`);
var regexValue = '\.*'+req.params.input+'*\.';
db.collection(myCollection).find({"full_name": {$regex: regexValue, $options: 'i'}}).toArray((err, members) => {
if(err) return console.log(err)
console.log(members);
res.render('search/list', {members: members});
})
});
I want them to be able to type in a text box and have it go directly do this endpoint. I have a very simple text box like this:
<form action="/search/">
<input type="text" name="firstname" ><br>
<input type="submit" value="Submit">
</form>
My problem is I don't know a clean way to get the submitted string from the text box into the request parameter.
With a Express Route app.get('/search/:input', function(req, res){ then :input is a path paramaters input, but your html form is going to make a GET request /search/?firstname=firstname_value, the request will not maching to the Route.
Use app.get('/search', function(req, res){ instead of your current code, then console.log(get request to: /members/${req.query.firstname}); if you want to use GET method.
(I don't know why log show /members/ ??? while route setting is /search/)
You can pass the inputbox value using ajax get method, access the value using req.params.input .Below is the code that I have tried.
app.js
app.get('/:input', function(req, res) {
console.log(req.params.input);
});
index.ejs
<!DOCTYPE html>
<html>
<head>
<title>Page Title</title>
</head>
<body>
<input type="text" name="firstname" id="firstname" ><br>
<input type="button" value="search" id="search">
<script src="http://code.jquery.com/jquery-3.3.1.min.js"></script>
<script>
$('#search').click(function(){
var firstname = $('#firstname').val();
$.ajax({
url: "http://localhost:3000/users/"+firstname,
method: 'get'
}).done(function() {
});
})
</script>
</body>
</html>

Having internal server error in my nodejs code

i am currently having internal server error and i don't know why it occurs since i am a newbie in this field. Can anyone explain what is going on here and suggest me a possible way to fix my code ?.Oh, and off - topic a little, i don't know exactly what i have to do to be fluently in making a connection between nodejs server and ajax, can any one help me with that?. Please don't erase this. Thanks you a lot
Here is my nodejs server:
var express = require("express"),
bodyParser = require("body-parser"),
data = require("nedb");
var app = express(),
db = new data({filename:'infors'});
app.use(bodyParser.urlencoded({extended:false}));
app.use(bodyParser.json());
app.use(express.static("public"));
app.get("/",function(req,res){
res.sendfile("html.html");
});
app.post("/login",function(req,res){
var user = req.body.user,
pass = req.body.pass;
db.insert({user:user,pass:pass});
res.end("login sucessful");
});
app.listen(3000);
Here is my html file:
<!DOCTYPE html>
<html>
<head>
</head>
<body>
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<script>
$(document).ready(function(){
var user,pass;
$("#button").click(function (){
user = $("#text").val();
pass = $("#text2").val();
$.post("http://localhost:3000/login",{user:user,pass:pass},function(data){
if(data == "done"){
alert("login success");
}
});
});
});
</script>
<fieldset>
<input type="text" id="text"/>
<input type="text" id="text2"/>
<input type="button" id="button" value="press here"/>
</fieldset>
</body>
</html>

Implementing simple upvote downvote program

I am using express.js and jQuery to create a basic upvote downvote program. Basically the voting buttons increment/decrement by one whenever pressed and the result of each button click is displayed below. Nothing happens when the buttons are clicked, not even a Cannot POST /. I am not sure what is causing the error. This is what my main.js file looks like:
$(document).ready(function(){
$("#up").click(function(){
var up = $.post("/upvote", {changeBy: 1}, function(dataBack){
$("#upvote").text(dataBack);
});
});
$("#down").click(function(){
var down = $.post("/downvote", {changeBy: 1},
function(dataBack){
$("#downvote").text(dataBack);
});
});
});
and then on the server side server.js, I have this:
var express = require("express");
var app = express();
var bodyParser = require("body-parser");
app.use(bodyParser.urlencoded({extended: true}));
app.use(express.static("public"));
var inc = 0;
var dec = 0;
app.post("/upvote", function(req, res){
res.setHeader("Content-Type", "application/json");
inc += parseFloat(req.body.changeBy);
res.write(JSON.stringify(inc));
res.end();
});
app.post("/downvote", function(req, res){
res.setHeader("Content-Type", "application/json");
dec -= parseFloat(req.body.changeBy);
res.write(JSON.stringify(dec));
res.end();
});
var server = app.listen(8081, function () {
var host = server.address().address
var port = server.address().port
console.log("Example app listening at http://%s:%s", host, port)
})
A bit of HTML:
<div class="buttons">
<button id="down">Downvote</button>
<p id="downvote"></p>
<button id="up">Upvote</button>
<p id="upvote"></p>
</div>
I used your code to create a jsfiddle and it seems to be working fine with click events. Of course the ajax calls error out but the click event handler itself seems to be called Chrome at least.
<div class="buttons">
<button id="down">Downvote</button>
<p id="downvote"></p>
<button id="up">Upvote</button>
<p id="upvote"></p>
</div>
$(document).ready(function(){
$("#up").click(function(){
var up = $.post("/upvote", {changeBy: 1}, function(dataBack){
$("#upvote").text(dataBack);
});
});
$("#down").click(function(){
var down = $.post("/downvote", {changeBy: 1},
function(dataBack){
$("#downvote").text(dataBack);
});
});
});
https://jsfiddle.net/j14qkyae/
i gave this a try and it works. Is this really the whole html you use? Then this is the error. You need to in include jquery and your main.js into the html. I copied a query.min.js into the public directory of the server.
<html>
<head>
<title>Up Down Vote</title>
<script src="jquery.min.js"></script>
<script src="main.js"></script>
</head>
<body>
<div class="buttons">
<button id="down">Downvote</button>
<p id="downvote"></p>
<button id="up">Upvote</button>
<p id="upvote"></p>
</div>
</body>
</html>

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