When developing a website and doing some server-side stuff with NodeJS can NodeJS be used on the command-line only or can it be used for scripting too? For example creating a script and doing all my NodeJS stuff in there and then including the script in my HTML without the command-line or is this not possible?
You can't embed Node.js in a webpage, but browsers have built in JavaScript runtimes so you don't need to embed another one.
You can't use Node.js specific APIs from JavaScript in a webpage. Most of them have serious security implications (such as providing a means for JavaScript to access the filesystem).
You can use Node.js to run an HTTP server, which you can then access from the browser (both directly and via XMLHttpRequest).
try node-browserify # https://github.com/substack/node-browserify, which i guess a bit closer to what you wanted here.
Related
I have an application that I need to deploy that is a mix of pure PHP, JavaScript, jQuery, and AJAX. It runs flawlessly on all machines when called in a browser. Unfortunately, I also need to deploy this application to a machine that won't be able to run a browser.
Just running the file using PHP will output the resulting file, but does not execute any of the Javascript.
What are my options to get this task running? The machine will have access to xampp, but not to a browser.
Edit: the application grabs data from MSSQL, uses Javascript to turn that data into charts, uses an AJAX call to save those files to disk, and then calls another PHP script to mail a copy of the resulting files.
It depends on what your exact Javascript needs are, but unfortunately, if your application truly depends on a browser (and can't be ported to something more appropriate for the constraint), you will need to "fake" the browser somehow. Here are a few options.
PhantomJS is basically a headless Webkit engine (think Chrome or Safari).
HtmlUnit for a Java based solution, supported/developed by Mozilla
Other rabbit holes (Wikipedia/Headless Browser)
NodeJS offers a non-browser, headless, Javascript specific option, but will require your code to be more robust and generic than many code bases initially are when originally coded for browsers.
Is it possible with Javascript or jQuery to convert mp3, wav, etc. to m4r format?
Let's assume you had a library that can change the format of files.
Let's also assume you only need the application to work on current browsers that implement FileAPI or FileReference so you can have access to uploaded files (you can't have access to them without FileAPI or FileReference unless you use Flash or Java Applets or equivalent technologies).
You wouldn't be able to write the output file back to the user because JavaScript is not allowed to access the local filesystem.
Your only solution would become sending the converted file to the server and the server sending it back to you with a force download directive so that the user will be prompted to download the results.
Now back to if there were a library that can the conversion (or even native JavaScript)... I haven't heard of any. It's not impossible to build one but it is impractical and wouldn't run very fast.
Edit:
Let's not forget Node.js!
It's a backend server that uses Google Chrome's V8 JavaScript interpretor/compiler. And it runs JavaScript as a backend scripting engine.
You have access to filesystem, databases and everything if you use that (or any other backend system for that matter) and still be using JavaScript. You can use libraries too. Either written in JavaScript or libraries written in other languages that have been linked to interface with Node.js.
Edit 2:
There is a PC emulator written entirely in JavaScript. It runs binary executables if you want it to. It's called JSLinux.
If you're feeling particularly rambunctious you can grab the ffmpeg binary executable (compiled with static linking). And embed it into your application code as an uuencoded string then use JSLinux to execute the commands and grab the results.
Indeed, it is possible doing this on the client using the latest js technologies. A web-worker thread can do the work in the background. At least in Firefox and Chrome it is also possible to read ("upload in memory") and write ("download from memory") files using the new W3C File API, see here.
I managed to read files via drag&drop from and within the client using google's GWT which in the end is plain javascript, so it must also be possible to do it "natively".
Besides that, the conversation algorithm of course has to be implemented in a javascript web worker to avoid blocking the gui. This should be the hardest part, but not impossible, though.
You would need a backend to do this. You may want to look into the PHPExtension of FFmpeg
Is it possible to list the files in a directory using only javascript? To clarify, I mean list the files on the server, not the files on the clients computer. For instance:
www.domain.com/files/
contains 4 images (.jpg)
Can I make an extra page (www.domain.com/files/list.html) that lists those 4 files using javascript?
No, Javascript doesn't have access to the filesystem. Server side Javascript is a whole different story but I guess you don't mean that.
Very late to this party, but my google search for this exact request led me here.
The answer is "not really", but I've found the frankenstein of hacks elsewhere: If +Indexes is (or can be) enabled in the .htaccess for the folder containing the files you want to list, then use XMLHTTPRequest with the folder name as the url (which will return an html page listing the files).
I don't know if you architecture allows it but ikf you can install and use node.js as its node API mentions, you can interact with the filesystem by requiring the fs module.
This is the environment Node.js relies on:
Node eventually wants to support all
POSIX operating systems (including
Windows with MinGW) but at the moment
it is only being tested on Linux,
Macintosh, and Solaris. The build
system requires Python 2.4 or better.
V8, on which Node is built, supports
only IA-32 and ARM processors. V8 is
included in the Node distribution. To
use TLS, OpenSSL are required. There
are no other dependencies.
You can run It side-by-side with another web app. and this will avoid blocking your web application if the interaction with the filesystem takes too long.
It is generally not a good idea to access client computer files via javascript for security reasons, however i suspect you can use the File System Object for that. I am not sure about browser-compatibility for that, it should work in IE only probably though.
You need to use server-side languages such as PHP, ASP.Net, JSP, etc
JavaScript runs inside a host environment. So if the host provides a facility to list files in this manner, then yes. But in the typical scenario where JavaScript is running in a browser with default configuration, no.
I'm writing a web crawler (web spider) that crawl all links in a website.
My application is a Win32 App, written in C# with .Net framework 3.5.
Now I'm using HttpWebRequest an HttpWebResponse to communicate with the web server.
I also built my own Http Parser that can parse anything I want.
I found all link like "href", "src", "action"... in the parse.
But I can not solve one problem: Simulate Client Script in the page (like JS and VBS)
For example, if a link like:
a href = "javascript:buildLink(1)"
... with buildLink(parameter) is a Javascript function that will make a custom link due to the parameter.
Please help me to solve this problem. How to simulate JavaScript in this app? I can parse the HTML source code and take all JavaScript code to another file, but how to simulate a function of it?
Thanks.
Your only real option is to automate a browser. As other answers have said, you cannot reliably simulate browser javascript without having a complete DOM.
There are fortunately ways to automate the browser, check out Selenium.
It has a C# API, so you can control the browser from C#.
Use your .NET web crawler code to crawl the site. Whenever you encounter a href="javascript:... link, handle the page containing the link in Selenium:
Use the Selenium API to tell the browser to load the page.
Use the Selenium API to find all links on the page.
This way, your spider only uses Selenium when necessary (pages without javascript links can be handled by the browser-less spider code you already got). And since this is an embarrassingly parallel workload, you could easily have multiple Selenium processes running at the same time (either on one computer or on other computers).
But remember that href="javascript is hardly the only way a page can have dynamic links. The more common case is probably that a onload or $(document).ready() script manipulates the DOM and adds links that way.
To catch that case (and others), the spider probably will have to use Selenium for all pages that have a <script> tag.
You are basically pretending to be a browser, except that HttpWebRequest only does the networking stuff for you.
I would recommend using the ie web browser control and interop'ing into that from your c# application. That will allow you to run JavaScript, set variables, post, etc etc.
Here's some basic links I found after a search for "ie web browser control":
http://www.c-sharpcorner.com/UploadFile/mahesh/WebBrowserInCSMDB12022005001524AM/WebBrowserInCSMDB.aspx
http://support.microsoft.com/kb/313068
This is a problem which is not easily solved. You could consider taking one of the existing JavaScript implementations and porting or interfacing with it somehow.
If I were tackling this problem, I'd probably build a small side application in Java on top of Rhino, with some sort of RPC framework layered on top of that so that I could communicate with it from my primary application.
Unfortunately, without having a complete DOM implementation on top of that, you would be limited to only very simple javascript.
You could execute the javascript by using the MS JScript engine or something similar.
MSDN Reference
Eric Lippert's blog on using Eval (part 1) (part 2) (part 3)
This isn't guaranteed to work, especially if the javascript tries to access the DOM, or somesuch... But for simple scripts, it might be enough.
I need to edit an xml file using javascript. Now I'm involved in a project of online testing.
The question.xml file is already in the project folder.
In that i want to add or edit the questions(only using javascript). I'm able to bring the particular content through ajax, but I am not able to edit the file.
Javascript can't write to a file. The best you'll be able to do is get Javascript to read and edit the XML then post that data to a server-side script to write to file.
Until now, Google Chrome is the only web browser that has a functioning implementation of the FileSystem API, therefore, it may allow you to save files locally using only Javascript.
Obviously, for security reasons, when writing files to the local file system, the user must explicitly allow it.
A working tutorial: http://www.html5rocks.com/en/tutorials/file/filesystem/
Nickf is correct. The reason Javascript can't write to a file is because it is a Client-Side language. Javascript will never have permission to write a file because it has to operate inside the browser sandbox.
You will need to use a server-side script (.NET, PHP, ColdFusion, etc) to write the file.
If you are willing to use Google Gears, you get a sandbox on the client machine on which you can write files.
Javascript has no built-in file I/O (a.k.a. you can't do it with JS alone)
Instead use some kind of server side language such as PHP or ASP.NET in conjunction with Javascript's AJAX functionality.
Look over Adobe's Flex development system. There are ways you can use it to build an app that runs in the browser (or not) and can access the filesystem (Windows/Mac/Linux). It's programmed in ActionScript, a dialect of javascript; and can interoperate with javascript in the browser.