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Why is the server response incorrect when the request is read correctly?

I'm on the Node.js repl, I created a new project folder and initialized the NPM, then I installed the Express package and wrote the following code into the js file:
const express = require('express');
const app = express();
app.listen(5000, function(){
console.log("server started on port 5000");
})
app.get("/", function(req, res){
res.send("Hi There! Welcome!")
})
app.get("/speak/:animalName", function(req,res){
var animalName = req.params.animalName;
var verso = "verso";
if (animalName = "pig"){
verso = "oink"
} else if (animalName = "dog"){
verso = "bau"
} else if (animalName = "cat"){
verso = "Miao"
}
console.log(req.params);
res.send("THE " + animalName + " says " + verso);
})
app.get("*", function (req, res){
res.send("Sorry, the page cannot be found")
})
When I open the js file with Nodemon the server starts correctly and when I type a specific pattern in the URL field the console.log returns me the req.params correctly (in the example below: for I typed "cat" the console returned { animalName: 'cat' }
Nonetheless, the response in the browser is not the correct one:

You're using a single = in your conditions. This always assigns the variable, instead of testing for equality. Use == or ===.

issue child process inside a server on node.js

I have an executable library in C (sudo ./ads1256_test adc.txt) where data are acquired from an ADC, likewise these data are automatically save in a text file (adc.txt).
On the other hand, I have a server in node.js (see code) in which would like to execute this program when a button in the website is pressed. For this, I tried to implement this process using the child process .exec('sudo ./ads1256_test adc.txt') but it did not work. It apparently runs but the values saved in the file are always zero. That is totally different to the obtained result when I execute the same command in terminal. I would appreciate if anybody could help me.
//Importing the core modules
var express = require('express');
var path = require('path');
var sys = require('sys');
var fs = require('fs');
var util = require('util');
var sleep = require('sleep');
var app = express();
var exec = require('child_process').exec;
var spawn = require('child_process').spawn;
app.get('/', function(req,res){
res.sendFile(path.join(__dirname + '/public/index.html'));
});
//Static Directories
app.use(express.static(__dirname + '/public'));
app.post('/test', function (req, res) {
exec('sudo ./ads1256_test adc.txt');
});
//Server Starting
var server = app.listen(8080, function(err){
if(err){
console.log('Error starting http server');
} else{
console.log('Sever running at http://localhost:8080 ');
}
});

first thing first, fix your code to
- asynchronously handle the cp spawn
- show errors
Example with tree, may you adapt it to your binary and check the response, it should help you go forward.
app.post('/test', function (req, res) {
var cp = spawn('tree', []);
cp.stdout.pipe(res);
cp.stderr.pipe(res);
cp.on('close', function () {
res.end();
cp.stdout.unpipe();
cp.stderr.unpipe();
});
});

(crypto.js) TypeError: Data must be string or buffer

I am currently using crypto.js module to hash things. It was working for a while then I started getting this error:
Here is the foundation of my server:
process.stdout.write('\033c'); // Clear the console on startup
var
express = require("express"),
app = express(),
http = require("http").Server(app),
io = require("socket.io")(http),
path = require("path"),
colorworks = require("colorworks").create(),
fs = require("fs"),
crypto = require("crypto");
function md5(msg){
return crypto.createHash("md5").update(msg).digest("base64");
}
function sha256(msg) {
return crypto.createHash("sha256").update(msg).digest("base64");
}
http.listen(443, function(){
// Create the http server so it can be accessed via 127.0.0.1:443 in a web browser.
console.log("NJ project webserver is running on port 443.");
// Notify the console that the server is up and running
});
app.use(express.static(__dirname + "/public"));
app.get("/", function(request, response){
response.sendFile(__dirname + "/public/index.html");
});
I am aware that these functions are creating the problem:
function md5(msg){
return crypto.createHash("md5").update(msg).digest("base64");
}
function sha256(msg) {
return crypto.createHash("sha256").update(msg).digest("base64");
}
The problem being, if these functions don't work (which they don't anymore), roughly 200 lines of code will go to waste.

This error is triggered by attempting to hash a variable that does not exist:
function md5(msg){
return crypto.createHash("md5").update(msg).digest("base64");
}
function sha256(msg) {
return crypto.createHash("sha256").update(msg).digest("base64");
}
md5(non_existent); // This variable does not exist.

What kind of data are you trying to hash ? Where does it come from ?
I would check the value of msg first then I would try :
crypto.createHash('md5').update(msg.toString()).digest('hex');
You could also use these packages instead:
https://www.npmjs.com/package/md5
https://www.npmjs.com/package/js-sha256

Node.js. Error: module is not a function

i have a main file -- index.js:
var express = require('express');
var app = express();
var request = require('request');
var demo = require('demo');
// This app will only respond requests to the '/scrape' URL at port 3000.
app.get('/scrape', function (req, res) {
var url = "http://www.l.com";
request(url, function (error, response, html) { // two parameters: an URL and a callback
if (!error) {
demo(html);
}
});
});
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);
});
and my module is demo.js:
module.exports = function (html) {
....
return JSON.stringify(json);
}
The error is :
TypeError: demo is not a function
I am new to node.js, i would like to know why this didn't work. Maybe i dont understand the real principle of module?
Thank you for answer me first.

You're not exporting your module properly. It should be:
exports.demo = function ....

Try to include your demo module in index.js:
var demo = require('./demo.js');

For the other freshers who use module in node.js for the first time.
first, made a new module called the name of your module.js
Second, it is not necessary to do "
npm install demo --save", if you want, it is also okay.
Third, in the main js which u want to call this module, focus on the name and the path of the module, you should write var anyName = require('the name of your module');, if they are in the same directory, you should write like this: var anyName = require('./the name of your module');

Send code via post message is not working

I wanted to send code to some node application and I use the postman with post message and in the body I put the following:
module.exports = function() {
var express = require('express'),
app = express();
app.set('port', process.env.PORT || 3000);
return app;
}
in the header of the request I put
content-Type application/text/enriched
in the node code I use the following
module.exports = function (app) {
fs = require('fs');
var bodyParser = require('body-parser');
...
app.post('/bb',function(req,res){
var fileContent = req.body
and the file content is empty ,I was able to see that it works since it stops in debug

If you want to add a custom content type then you need to keep two things in mind:
Content type couldn't be "application/text/enriched", in other hand "application/text-enriched" is ok. Max two "words".
You must provide a custom accept header on body parser configuration BUT body parser return you a buffer when you use custom header
See the example:
var express = require('express')
var app = express()
var bodyParser = require('body-parser')
app.use(bodyParser.raw({ type: 'application/text-enriched' }))
app.post('/demo', function(req, res) {
console.log('POST DATA')
console.log('STREAM', req.body)
console.log('STREAM to STRING', req.body.toString())
res.status(200).send('ok');
});
app.listen(3000);
You can test in your console with curl:
curl 'http://localhost:3000/demo' -d 'name=john&surname=doe' -H 'Content-Type: application/text-enriched'
I recommend you try to not use a custom content type header because things are easier. I hope that my explanation help you.