memory error in node JS (node::smalloc::Alloc) - javascript

I'm new to node Js, I've build a really simple server that send me back a zip file I request. It's all working but after some request a crash occur and i visualize this message on the terminal :
FATAL ERROR: node::smalloc::Alloc(v8::Handle, size_t, v8::ExternalArrayType) Out Of Memory
var http = require('http');
var url = require('url');
var fs = require('fs');
var port = 1337;
// create http server
var server = http.createServer(function (request, response) {
var path = require('url').parse(request.url, true);
console.log('requested ' + path.pathname);
//get zipped resoures
if (path.pathname == '/getzip') {
console.log(request.url);
var queryData = url.parse(request.url, true).query;
if (queryData.name) {
var filename = queryData.name;
//open corrisponding file
var zipFile = fs.readFileSync('packets/' + filename);
response.writeHead(200, {
'Content-Type': 'application/x-zip',
'Content-disposition': 'attachment; filename=data.zip'
});
//send file in response
response.end(zipFile);
}
else {
response.writeHead(200, {'Content-Type': 'text/plain'});
response.end('{error = "bad url"}');
}
}
}).listen(port);
server.timeout = 1000000;
Do you have any idea of what it can be? this code looks so simple.

Instead of reading the entire file into memory, you should leverage streams for this:
response.writeHead(200, {
'Content-Type' : 'application/x-zip',
'Content-disposition' : 'attachment; filename=data.zip'
});
fs.createReadStream('packets/' + filename).pipe(response);

Related

Sending GET with parameters to HTTP server

I'm trying out the code basics and want to write some basic client-server app.
I have an HTML page where user inputs two numbers (num1 and num2) then it passes to JS which passes it to HTTP server written with NodeJS. On the server the numbers should be added and returned to the HTML page. But the server returns this error:
ReferenceError: num1 is not defined
What is wrong with the code?
Here is the JS code:
function myFunction(num1, num2) {
var xhttp = new XMLHttpRequest();
xhttp.onreadystatechange = function() {
if (this.readyState == 4 && this.status == 200) {
num1 = Math.floor(num1);
num2 = Math.floor(num2);
document.getElementById("result").innerHTML = this.responseText;
}
};
xhttp.open("GET", "http://localhost:8080?num1=2&num2=3", true);
xhttp.send();
}
And here is the NodeJS code:
var http = require('http');
http.createServer(function (req, res) {
var resnum = 2 + req.params(num1) + req.params(num2);
res.writeHead(200, {'Content-Type': 'text/html'});
res.write(resnum);
res.end();
}).listen(8080);
You have to use the url module https://nodejs.org/api/http.html#http_message_url
var http = require('http');
var url = require('url');
http.createServer(function (req, res) {
var params = url.parse(req.url, true).query;
var resnum = 2 + params.num1 + params.num2; //or 2 + parseInt(params.num1) + parseInt(params.num2)
res.writeHead(200, {'Content-Type': 'text/html'});
res.write(resnum);
res.end();
}).listen(8080);
If you want a concise code like yours you need to use some module like Express framework.
var express = require('express')
var app = express()
app.get('/', function (req, res) {
const resnum = 2 + parseInt(req.query.num1) + parseInt(req.query.num2);
res.writeHead(200, {'Content-Type': 'text/html'});
res.end(resnum.toString())
})
app.listen(8080)
When you are using 'http' module only, the only thing you have to work with is req.url. You could try hard and get the parameters by breaking down the url but you would have a lengthy code:
var http = require('http');
http.createServer(function (req, res) {
const step1 = req.url.split('?')[1] //step1 = num1=2&num2=3
const step2 = step1.split('&') // step2 = [num1=2,num2=3]
let result = {};
step2.forEach((val) => { //break down strings further and put into result object
const value = val.split('=')
result[value[0]] = value[1]
})
var resnum = 2 + parseInt(result.num1) + parseInt(result.num2);
res.writeHead(200, {'Content-Type': 'text/html'});
res.end(resnum.toString());
}).listen(8080);
Some notes:
You get that error because num1 is a variable argument to a
function. However we don't have a variable num1 declared.
Parameters come as strings so unless you parse them into integers,
you will have string concatenation and 223 as a result
res.write and res.end need a
string input so you need to parse back to string after calculations.

Formidable is not defined in Node.js

I am trying to create an HTTP server that the user can upload images and archives, and for that I am using formidable for handling the upload part.
My code :
requestHandler.js
// Request Handlers (will handle all requests that happen)
// Allows Node.js to make use of a non-blocking operation: exec ();
var exec = require("child_process").exec;
var querystring = require("querystring");
fs = require("fs");
var fomidable = require("formidable");
function start(response, postData) {
console.log("Request handler 'start' was called");
var body = '<html>' +
'<head>' +
'<meta http-equiv = "Content-Type" content = "text/html";'+
'charset="UTF-8"/>' +
'</head>' +
'<body>' +
'<form action = "/upload" enctype = "multipart/form-data"' +
'method = "post">' +
'<input type ="file" name = "upload multiple = "multiple">' +
'<input type = "submit" value ="Upload file" />' +
'</form>' +
'</body>' +
'</html>';
response.writeHead(200, {"Content-Type" : "text/html"});
response.write(body);
response.end();
}
// What is being passed between router.js and requestHandler.js is the entire body of the POST data request.
function upload(response, request) {
console.log("Request handler 'upload' was called");
var form = new formidable.IncomingForm();
console.log("about to parse");
form.parse(request, function(error, fields, files) {
console.log("parsing done");
/*Possible error on Windows systems; tried to rename to an already existing file*/
fs.rename(files.upload.path, "/tmp/test.png", function(err) {
if(err) {
fs.unlink("/tmp/test.png");
fs.rename(files.upload.path, "/tmp/test.png");
}
});
response.writeHead(200, {"Content-Type" : "text/plain"});
response.write("You've sent the text : " + querystring.parse(postData).text);
response.write("\nHello Upload");
response.end();
});
}
function show(response) {
console.log("Request handler 'show' was called.");
fs.readFile("/tmp/test.png", "binary", function(error,file) {
if(error) {
response.writeHead(500, {"Content-Type" : "text/plain"});
response.write(err + "\n");
response.end();
} else {
response.writeHead(200, {"Content-Type" : "image/png"});
response.write(file, "binary");
reponse.end();
}
});
}
exports.start = start;
exports.upload = upload;
exports.show = show;
I am using too formidable in the another part of my code, in my server.js but there for some reason works (And for that reason I am not posting the code), the error point out to requestHandler.js in line 35 :
var form = new formidable.IncomingForm();
formidable is not defined
How can I make formidable defined ? When I am already doing that calling in the first place in :
var formidable = require("formidable");
I think you have a typo...
var fomidable = require("formidable");
Should probably be:
var formidable = require("formidable");
Hence the formidable is not defined... you defined it as fomidable.

Image not displaying when loading HTML page through Node server

Heads up: I am very new to Node.js, so this code might not be the best way to do it all. I am still in the learning process.
When I run the .JS file through node and go to the localhost:1337, all of the HTML shows up correctly, but the image does not render. when i look in the source code, the image is being brought in as Text/HTML and not an image.
Why is this? Is that why the image is not being displayed?
This is my code so far.
var http = require('http'),
fs = require('fs'),
request = require('request'),
url = require('url');
http.createServer(function (req, res)
{
console.log(req.url);
var request = url.parse(req.url, true),
action = request.pathname,
html = buildHtml(req);
res.writeHead(200, {'Content-Type': 'text/html','Content-Length': html.length,'Expires': new Date().toUTCString()});
res.end(html);
}).listen(1337, '127.0.0.1');
console.log('Server running at http://127.0.0.1:1337/');
function buildHtml(req)
{
var header = "",
body = '<img src="../Dilbert.jpg" alt="Dilbert">';
return '<!DOCTYPE html>'
+ '<html><header>' + header + '</header><body>' + body + '</body></html>';
};
var download = function(uri, filename, callback)
{
request.head(uri, function(err, res, body)
{
console.log('content-type:', res.headers['content-type']);
console.log('content-length:', res.headers['content-length']);
request(uri).pipe(fs.createWriteStream(filename)).on('close', callback);
});
};
download('http://assets.amuniversal.com/145cd9c0fb4e0132ee37005056a9545d', 'Dilbert.jpg', function(){
console.log('done');
});

detect ajax request to normal request node js

hello h have the next code and i like to know how to detect between an ajax request to a normal request? without express.
var http = require('http');
var fs = require('fs');
var path = require('path');
var url = require('url');
http.createServer(function (request, response) {
console.log('request starting...');
console.log("request.url = " + request.url);
console.log("url = "+ url);
response.setHeader('content-Type','application/json');
var filePath = '.' + request.url;
if (filePath == './')
filePath = './index.html';
var extname = path.extname(filePath);
var contentType = 'text/html';
switch (extname)
{
case '.js':
contentType = 'text/javascript';
break;
case '.css':
contentType = 'text/css';
break;
}
fs.exists(filePath, function(exists) {
if (exists)
{
fs.readFile(filePath, function(error, content) {
if (error)
{
response.writeHead(500);
response.end();
}
else
{
console.log("contentType = "+contentType);
response.writeHead(200, { 'content-Type': contentType });
response.end(content, 'utf-8');
}
});
}
else
{
response.writeHead(404);
response.end();
}
});
}).listen(8081);
console.log('Server running at http://localhost:8081/');
in the client side i send an ajax request but i ask from the browser request to.
You can check request.headers if it contains HTTP_X_REQUESTED_WITH.
If HTTP_X_REQUESTED_WITH has a value of XMLHttpRequest then it is an ajax request.
Example:
if (request.headers["x-requested-with"] == 'XMLHttpRequest') {
//is ajax request
}
I came across this question and I know it's old but in case someone needs the answer and the idea behind it.
Usually, on the client side, when you make an AJAX request you add a key and value that describe the content i.e: 'content type':'application/json'
So simply, on the server side, you can test the header if it contains application/json as the content type then you are safe to say it's an ajax request.
req.headers['content-type'] == 'application/json'

Problem receiving response from node server using ajax post request

I have written a http server using node js
var sys = require("sys"),
http = require("http"),
url = require("url"),
path = require("path"),
fs = require("fs");
http.createServer(function(request, res) {
var parsed_url = url.parse(request.url);
var uri = parsed_url.pathname;
if(uri === "/test"){
res.writeHead(200, {'Content-Type': 'text/javascript'});
request.addListener('data', function (chunk) {
var data = eval("(" + chunk + ")");
console.log(data[0].id);
})
request.addListener('end', function() {
console.log('end triggered');
res.write("Post data");
res.end();
});
}
}).listen(8080);
and i am trying to send back response of ajax request but i am unable to receive any response. Here is the code for ajax request ,
var myhttp = new XMLHttpRequest();
var url = "http://localhost:8080/test";
var data = [{"a":"1"},{"b":"2"},{"c":"3"}];
var dataJson = JSON.stringify(data);
myhttp.open('POST', url, true);
myhttp.send(dataJson);
myhttp.onreadystatechange = function() {
if ((myhttp.readyState == 4) && (myhttp.status == 200)){
alert(myhttp.responseText);
}
else if ((myhttp.readyState == 4) && (myhttp.status != 200))
{
console.log("Error in Connection");
}
Can anyone help me what i am doing wrong ...
Thanks
Vinay
Your code is almost right but on your code sample you have
console.log(data[0].id)
the data object has no property id so if you only have
console.log(data[0])
there you have a response like
{ a: '1' }
therefore you can access the property a by doing
console.log(data[0].a);
UPDATED Updated with a full example
One more thing is that you are using eval and node comes with JSON.parse bundle with it so the snippet below is how i made it work
File: app.js
var sys = require("sys"),
http = require("http"),
url = require("url"),
path = require("path"),
fs = require("fs");
http.createServer(function(request, res) {
var parsed_url = url.parse(request.url);
var uri = parsed_url.pathname;
if(uri === "/test"){
res.writeHead(200, {'Content-Type': 'text/javascript'});
request.addListener('data', function (chunk) {
// removed this - eval("(" + chunk + ")");
var data = JSON.parse(chunk);
console.log(data[0].a);
})
request.addListener('end', function() {
console.log('end triggered');
res.write("Post data");
res.end();
});
} else if(uri === "/") {
fs.readFile("./index.html",function(err, data){
if(err) throw err;
res.writeHead(200, {'Content-Type': 'text/html'});
res.end(data);
});
}
}).listen(8080);
On the same directory create a file index.html with the following:
<html>
<head>
<script type="text/javascript" charset="utf-8">
var myhttp = new XMLHttpRequest();
var url = "http://localhost:8080/test";
var data = [{"a":"1"},{"b":"2"},{"c":"3"}];
var dataJson = JSON.stringify(data);
myhttp.open('POST', url, true);
myhttp.send(dataJson);
myhttp.onreadystatechange = function() {
if ((myhttp.readyState == 4) && (myhttp.status == 200)){
alert(myhttp.responseText);
}
else if ((myhttp.readyState == 4) && (myhttp.status != 200))
{
console.log("Error in Connection");
}
}
</script>
</head>
<body>
</body>
</html>
That is a complete working example of what you want.
With regards to the same origin policy issues you were having is mainly due to the fact that you cant POST data between 2 different domains via ajax unless you use some tricks with iframes but that is another story.
Also i think is good for anyone to understand the backbone of a technology before moving into frameworks so fair play to you.
good luck
You have to read the data in a different way. Posted data arrives on a node server in chunks (the 'data' event), that have to be collected until the 'end' event fires. Inside this event, you are able to access your payload.
var body = '';
request.addListener('data', function (chunk) {
body += chunk;
});
request.addListener('end', function() {
console.log(body);
res.write('post data: ' + body);
});
Additionaly, there seem to be some issues with your client-side code (especially concerning the status-code checks), but i can't really help you with those as i always work with frameworks like jQuery to manage async requests.
If you want to build reliable node.js servers for web use, i highly recommend the high-performance HTTP-Framework Express. It takes away alot of the pain when developing a web-based server application in node and is maintained actively.

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