How shall I understand and use this server written in Node.js?
Question
I am trying to understand a simple server written in node.js
var http = require('http');
var querystring = require('querystring');
http.createServer(function (req, res) {
switch(req.url) {
case '/form':
if (req.method == 'POST') {
console.log("[200] " + req.method + " to " + req.url);
var fullBody = '';
req.on('data', function(chunk) {
fullBody += chunk.toString();
});
req.on('end', function() {
res.writeHead(200, "OK", {'Content-Type': 'text/html'});
res.write('<html><head><title>Post data</title></head><body>');
res.write('<style>th, td {text-align:left; padding:5px; color:black}\n');
res.write('th {background-color:grey; color:white; min-width:10em}\n');
res.write('td {background-color:lightgrey}\n');
res.write('caption {font-weight:bold}</style>');
res.write('<table border="1"><caption>Form Data</caption>');
res.write('<tr><th>Name</th><th>Value</th>');
var dBody = querystring.parse(fullBody);
for (var prop in dBody) {
res.write("<tr><td>" + prop + "</td><td>" + dBody[prop] + "</td></tr>");
}
res.write('</table></body></html>');
res.end();
});
} else {
console.log("[405] " + req.method + " to " + req.url);
res.writeHead(405, "Method not supported", {'Content-Type': 'text/html'});
res.end('<html><head><title>405 - Method not supported</title></head><body>' +
'<h1>Method not supported.</h1></body></html>');
}
break;
default:
res.writeHead(404, "Not found", {'Content-Type': 'text/html'});
res.end('<html><head><title>404 - Not found</title></head><body>' +
'<h1>Not found.</h1></body></html>');
console.log("[404] " + req.method + " to " + req.url);
};
}).listen(8080);
What does the function req.on() do? For example, req.on('data',...) and req.on('end',...) ? Is this explained somewhere in https://nodejs.org/api/http.html ? I think I might have missed it.
How shall I send a HTTP request to the server so that the part inside case '/form': if (req.method == 'POST'){...} is executed? Specifically, when using curl , what arguments and options shall I give to curl ? What if using Firefox browser?
1 answers
solution1
1 2019-05-03 10:27:53
Req.on('data') means your server is receiving the data from the client, in callback attached to req.on('data') you generally concatenate the data and then parse the data to be used later. Once it has received the entire data then the callback attached to req.on('end') will be executed and here you can do all the business logic based on the data you received and then send the response back to the client
now how can you access the /form URL?
When sending data via a POST or PUT request, two common formats (specified via the Content-Type header) are:
- application/json
- application/x-www-form-urlencoded
you can either use postman client or curl to access the /form URL.
in curl-
curl -H "Content-Type:application/x-www-form-urlencoded" \
-d "param1=value1¶m2=value2" \
http://localhost:8080/form
curl -H "Content-Type:application/json" \
-d '{"key1":"value1", "key2":"value2"}' \
http://localhost:8080/form
In your code you are accepting the application/x-www-form-urlencoded so go with the first one
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