I want to check the performance of the gzip decoding speed in a web browser.
In the Java or c#, we can easily check the gzip decoding time.
But I can not measure the decoding time in the web browser.
plz help me.
I want to check some decoding speed of gzipped html files.
With JavaScript can I measure the performance.
In open source browsers like Chromium or Firefox you could have a look at the source code and insert some lines to record the time needed for decoding. If the browser uses a specific library for gzip decoding, you can of course also download that library and test it.
I don't think there's a way to get that time, especially in your own Javascript code : I suppose the decompression is done at a much lower-level (like somewhere arround the download/network layer of the browser) than the rendering of the page the execution of your Javascript code.
That would be the best solution for that compression to be totally transparent for the upper-layers : when rendering pages or executing JS code, there is absolutely no need for the browser to know that it's been received in a compressed form.
Maybe a solution, especially with Firefox, would be to develop some extension ?
Considering Firebug, for example, is able to kind of "hook" into the network layer, to display the information we get in the "Network" tab, I suppose you might be able to do sort of the same ?
In Google Chrome, you can check out the various properties of chrome.loadTimes().
You can do it using Fiddler - it has a time display for each HTTP transaction. Because Fiddler is a debugging proxy, it works with any browser. Windows only, though.
Related
I have latests CefGlue version (3.2272.2035)
I need to save current page as PDF. I'd like to interact with my CEF somehow (JS/C#) and make it create PDF for me.
I've tried to use javascript.window.print() for that purpose with no success, because, all i've got is such window.
I've found OnPrintJob method in CefPrintHandler but I don't know what is the right way to call it + comments say: "Implement this interface to handle printing on Linux"
and I need to handle printing to pdf on Windows environments (both x64/x86)
Any code example would be appreciated. Thanks in advance for any help.
You'd need to merge this patch and recompile cef from source; Besides, you might have to add some glue logic to CefGlue. I tested the patch myself (on C++ API) and it worked fine.
EDITED: the patch will be merged in trunk.
If you only need to print some pages (specially if these pages are under your control), you will do just fine. However if you need (as I did at the time) to print almost anything, you'll probably face the fact that some web pages don't render anything useful to the print view. Also, even those well-behaved diverge significantly from what you see on the screen - and that's not a CEF behavior, as even google chrome showed the same issues. In my application this was a no-go so I dropped printing and started capturing the screen (and implemented saving that to a pdf using a pdf library in C++), but perhaps your application isn't as demanding as mine was. Cheers!
We are currently planning a website on which people can upload movies. When looking at YouTube you notice that some movies are uploaded twice or more times (by different users). To scale our application we're thinking about the following idea:
User selects movie file to be uploaded
A JavaScript will get the SHA256 hash from the file (it's more accurate then the MD5 hash) before it get's uploaded
The website will check if the hash already exists
If the hash doesn't exist, the file will be uploaded
If the hash does exist a message will be prompted or a reference to the already existing version on the server will be created. This without the video being uploaded.
Q: How do we analyze a file with JavaScript in order to get the SHA256 hash, and is SHA256 good enough or should we consider SHA512 (or another algorithm)?
Use the HTML5 File API to read the file: http://www.html5rocks.com/en/tutorials/file/dndfiles. Here is a JS code for calculating SHA-256: http://www.webtoolkit.info/javascript-sha256.html
I must add that I never tried this, but it seems to be possible. Alxandr is right, this would take very long for large videos, but you may try to use the WebWorker API in order not to freeze the browser: http://html5rocks.com/en/tutorials/workers/basics
Putting files aside for now, if the question is actually whether it's possible to get a SHA-256 hashes in JavaScript, the answer is yes. You can either reiplement this yourself (bad idea) or use a library like the Stanford JS Crypto library (good idea).
As far as the File API goes, it is implemented in the bleeding edge version of every major desktop browser, as well as the latest Android browser shipping. iOS is not supported as it doesn't really have a filesystem. Check out caniuse.com for the latest stats.
Simple answer, you can't. That is if you want to support all browsers at least. I think both Chrome and FireFox supports the reading of files on the client, and IE supports it with the help of ActiveX controls, but to get a solution that works in all browsers you have to use a plugin like Flash or Silverlight. Also, when doing file-uploads of video-magnitude (large+ files), I think going for flash or the likes from the start is a good idea anyhow, but that's just my opinion.
I'm targetting a couple of web projects at mobile users, and noticed that some of the standard tools (JS libraries, json transfers, xml etc) are quite heavy for mobile data plans.
I'd like to be able to implement gzip'd resources, and probably mod_deflate/mod_gzip to try and reduce the amount of bandwidth used by these devices.
However, I don't know how widespread support for gzipped javascript, gzipped html etc. is on mobile devices, or even if it is common practice to use...? It seems to make sense though.
Is it ok to use as a solid tool for the common mobile devices..? iPhone, android, blackberry, windows mobile/opera..?
Thanks.
I don't think it matters, a browser will request GZipped data if it supports it, so your server will only GZip it if your browsers asks it to.
As far as I know most of them supports it, but if you configure you're server well it will be able to send non-compressed resources if needed.
Another benefit is that you improve caching as some devices like iPhone has limits of 25k for a content to be cached.
So the short answer is: Just Do It
mod_deflate / mod_gzip will check the client's "accept" headers and turn compression on or off accordingly.
Just turn it on in your server, and make sure your js and css resources get compressed as well. You can use Firebug's "Net" tab to check whether compression was applied to the loaded resources.
If compression is mising for certain file types, check out this question for how to turn it on.
Go for it - the gzipped version should be only sent if a browser sends an Accept-Encoding: gzip (and the modules check for this automatically). (see the relevant part of RFC 2616)
(the usual warning applies - some browsers are broken. For example, IE6 advertises gzip-capability but doesn't actually support it properly. For mobile browsers, I haven't encountered such brokenness yet - so far every mobile browser that advertised gzip supported it)
I want to show a PREVIEW kind of thing for an post , so took details by JS
but problem comes when it comes to <input type="file" , it's not giving full path to the file
Ex:
if I do
$("#image").val();
it only give "Sunset.jpg" not C:\Documents and Settings\All Users....\Sunset.jpg
any idea how to get that detail value?
Although, as others have already pointed out, you cannot learn the full path to the file in JavaScript, perhaps a completely different approach to the problem might still work for you.
You could upload the photo automatically as soon as the visitor has picked it (the behavior you see in GMail, among other applications), so it's residing on your server even as the visitor continues interacting with your page. At that point, showing a preview is as simple as serving one yourself from your own (now server-side) copy of the image.
This if for security reasons, so you cannot read files from the users system using JavaScript.
If you happen find a workaround, there will probably be security patches released by browser vendors sooner rather than later. I know because in earlier versions if IE, it was possible to read the full path and hence display a preview, at least if the file was an image. I used that in a CMS UI, but of course that nifty feature was ruined by an IE service release :-/
In general the file upload control is somewhat of a "black box" for security reasons. You have only very limited access to scripting and styling it. This is so you can't snoop or upload files without the user knowing, or so you cannot trick the user into uploading files with a deceptive interface.
This is now possible as of Firefox 3.6
https://developer.mozilla.org/en/DOM/FileList
Though the code they show does not seem to work in Chrome, so I'm guessing even the HTML5 JavaScript API for things like this has yet to be standardized.
This is a security feature. You cannot change or get the entire path in secure browsers, so what you want to do, cannot be done. If you use something like Flash, Silverlight or Java, then it should be relatively easy.
As far as I know, there is no way to do what you want to do in javascript. Its a pretty big security issue - having filesystem access in a browser.
There are a few browser plugins (java/flash/gears) that may allow you to do this sort of thing. I know with gears you can get the user to select a file - and open it to read the content using JS.
I have a JavaScript application that an user interacts with. I need to save the appearance of the interface at the current time, crop out the part that I need (or only shot the part that I need by specifying the div), and send it back to the server.
Clearly any external services would not be able to do this, I need a JavaScript (or Flash) script that can save the screen appearance. Is this possible?
Also, as the comment below says, I cannot use ActiveX.
Google is doing this in Google+ and a talented developer reverse engineered it and produced http://html2canvas.hertzen.com/ . To work in IE you'll need a canvas support library such as http://excanvas.sourceforge.net/
I think using JavaScript, you won't be able to due to the security restrictions. Flash, possibly.
It's impossible in pure JavaScript, without using ActiveX.
It is impossible using JavaScript (nor Flash). It depends on your constraints, and there are some workarounds.
You can take advantage of browser extensions (such as a Firefox add-on), but I guess it does not fit your requierments.
The best option I can think of is to construct the DOM tree on the client side, and then post it to remote server.
On the server side nothing really holds you from doing generally anything. Using WebKit or even launching Internet Explorer or Firefox, you can create the snapshot server-side.
It's far from elegant, but possible.