Develop Reference

How to display a PDF without downloading

I have a PDF like like this:
"http://centraldata.s3.amazonaws.com/.....pdf?AWSAccessKeyId=...."
which I get from an api call. Then I pass it into an link so that users can click and download it.
<a href={pdfUrl} />
So, my question is, is there a way to let user view the PDF without downloading it? Except passing the Url into an tag, I don't know if there is any other way to use this link

When you place a page of HTML in the Public Domain (World Wide Web) you are offering a service with Dis-positions (Download to later view this page after decoding download).
If you include images, text, audio, video or even a PDF via link, then you are offering to disposition a copy of the page content (be dispossessed of all with its content) from the server to the browser.
A web site can indicate to the browser that the download need not be viewed in the browser, (many browsers do not have a PDF viewer, or the browser may be secured to a safer setting such as Download Media ONLY) the HTTP response could include the html attachment headers:
Content-Type: application/pdf
Content-Disposition: attachment; filename="file.pdf"
A web site can indicate to the browser that the download need not be viewed in the browser, but there is a possibility if the user settings allow for inline viewing, (many browsers do not have a PDF viewer or it may be secured to a safer setting such as Download ONLY) the HTTP response should include the html attachment headers:
Content-Type: application/pdf
Content-Disposition: inline; filename="file.pdf"
To avoid problems with the text parsing of the optional filename (blob: or anything will be saved to filename at the discretion of the client dispossesser) then the proffered optional filename should be "double quoted".
User security settings should ideally be set to no-popups, like blanks, open secondary windows or target tabs, since those are unfriendly, anti-social server actions.
W3 Recommendation says
< a href="download-file.pdf" download >right click here for your options including view now< /a>
If you as my client have an inline PDF viewer active, here is an iframe should you wish to use it. (Your servant)
The next two related questions are
How can I stop that content I duplicated, from being duplicated as a copy by the client?, well clearly you cannot, since you willingly gave it away and once decrypted and decoded by the receiver it belongs to them as editable dis possessed content.
How can I mask the source URL ?, generally you can not since to decode the whole file and maintain it (if required) the sending caller ID must be maintained as an open comms channel during viewing. (Much like satellite download or Netflix recordings on demand.)

just use this
MyPDF

How do I download a file (instead of opening it) with JavaScript? [duplicate]

Is it possible to force a download through JS or Javascript i-e the web page should not open the file in new tab in the browser but to pop up to let the user to choose eith "save as" or open with ???

With the advent of HTML5 you could just use the new property download in the anchor tag.
The code will look something like
<a download="name_of_downloaded_file" href="path/to/the/download/file"> Clicking on this link will force download the file</a>
It works on firefox and chrome latest version. Should I mention that I didn't check it in IE? :P
Edited the download attribute after comment from sstur
https://caniuse.com/#feat=download

dynamic create link and click it with download attribute for force download as file:
var anchor = document.createElement('a');
anchor.href = this.props.download_url;
anchor.target = '_blank';
anchor.download = this.props.file_name;
anchor.click();
Take a notice that i didn't even added it to DOM, so it's fast.
P.S download attribute won't work with IE. But it will just open link in new tab.
http://caniuse.com/#feat=download

You can not force that behavior from JavaScript, the HTTP Headers need to be set on the server side:
Content-disposition=attachment; filename=some.file.name
The way you can solve the problem is to let your AJAX method redirect the user to the URL of the PDF:
location.replace('path/to.pdf');
(The above HTTP headers must be set for the PDF)
Update
At the time of this answer, it wasn't possible. Now it is, scroll down to see the other answer saying so.

No this is not possible with JQuery/JavaScript only.
You will need a server side script which returns you the file with a Content-Type (HTTP Header) which will force the browser to download your requested file. An possible value for Content-Type would be application/force-download.

No, it is not possible and thanks God it isn't. Otherwise I leave you to the imagination of what kind of files could be stored on your computer when you visit a web site without you knowing it.
As #Paul D. White pointed out in the comments section if you want to open the file inline (inside the browser) with the default program associated with it you could have the server send the Content-Disposition HTTP header. For example:
Content-Disposition: inline; filename=foo.pdf

Chrome extension: How to show custom UI for a PDF file?

I'm trying to write a Google Chrome extension for showing PDF files. As soon as I detect that browser is redirecting to a URL pointing to a PDF file, I want it to stop loading the default PDF viewer, but start showing my UI instead. The UI will use PDF.JS to render the PDF and jQuery-ui to show some other stuff.
Question: how do I make this? It's very important to block the original PDF viewer, because I don't want to double memory consumption by showing two instance of the document. Therefore, I should somehow navigate the tab to my own view.

As the main author of the PDF.js Chrome extension, I can share some insights about the logic behind building a PDF Viewer extension for Chrome.
How to detect a PDF file?
In a perfect world, every website would serve PDF files with the standard application/pdf MIME-type. Unfortunately, the real world is not perfect, and in practice there are many websites which use an incorrect MIME-type. You will catch the majority of the cases by selecting requests that satisfy any of the following conditions:
The resource is served with the Content-Type: application/pdf response header.
The resource is served with the Content-Type: application/octet-stream response header, and its URL contains ".pdf" (case-insensitive).
Besides that, you also have to detect whether the user wants to view the PDF file or download the PDF file. If you don't care about the distinction, it's easy: Just intercept the request if it matches any of the previous conditions.
Otherwise (and this is the approach I've taken), you need to check whether the Content-Disposition response header exists and its value starts with "attachment".
If you want to support PDF downloads (e.g. via your UI), then you need to add the Content-Disposition: attachment response header. If the header already exists, then you have to replace the existing disposition type (e.g. inline) with "attachment". Don't bother with trying to parse the full header value, just strip the first part up to the first semicolon, then put "attachment" in front of it. (If you really want to parse the header, read RFC 2616 (section 19.5.1) and RFC 6266).
Which Chrome (extension) APIs should I use to intercept PDF files?
The chrome.webRequest API can be used to intercept and redirect requests. With the following logic, you can intercept and redirect PDFs to your custom viewer that requests the PDF file from the given URL.
chrome.webRequest.onHeadersReceived.addListener(function(details) {
if (/* TODO: Detect if it is not a PDF file*/)
return; // Nope, not a PDF file. Ignore this request.
var viewerUrl = chrome.extension.getURL('viewer.html') +
'?file=' + encodeURIComponent(details.url);
return { redirectUrl: viewerUrl };
}, {
urls: ["<all_urls>"],
types: ["main_frame", "sub_frame"]
}, ["responseHeaders", "blocking"]);
(see https://github.com/mozilla/pdf.js/blob/master/extensions/chromium/pdfHandler.js for the actual implementation of the PDF detection using the logic described at the top of this answer)
With the above code, you can intercept any PDF file on http and https URLs.
If you want to view PDF files from the local filesystem and/or ftp, then you need to use the chrome.webRequest.onBeforeRequest event instead of onHeadersReceived. Fortunately, you can assume that if the file ends with ".pdf", then the resource is most likely a PDF file. Users who want to use the extension to view a local PDF file have to explicitly allow this at the extension settings page though.
On Chrome OS, use the chrome.fileBrowserHandler API to register your extension as a PDF Viewer (https://github.com/mozilla/pdf.js/blob/master/extensions/chromium/pdfHandler-vcros.js).
The methods based on the webRequest API only work for PDFs in top-level documents and frames, not for PDFs embedded via <object> and <embed>. Although they are rare, I still wanted to support them, so I came up with an unconventional method to detect and load the PDF viewer in these contexts. The implementation can be viewed at https://github.com/mozilla/pdf.js/pull/4549/files. This method relies on the fact that when an element is put in the document, it eventually have to be rendered. When it is rendered, CSS styles get applied. When I declare an animation for the embed/object elements in the CSS, animation events will be triggered. These events bubble up in the document. I can then add a listener for this event, and replace the content of the object/embed element with an iframe that loads my PDF Viewer.
There are several ways to replace an element or content, but I've used Shadow DOM to change the displayed content without affecting the DOM in the page.
Limitations and notes
The method described here has a few limitations:
The PDF file is requested at least two times from the server: First a usual request to get the headers, which gets aborted when the extension redirects to the PDF Viewer. Then another request to request the actual data.
Consequently, if a file is valid only once, then the PDF cannot be displayed (the first request invalidates the URL and the second request fails).
This method only works for GET requests. There is no public API to directly get response bodies from a request in a Chrome extension (crbug.com/104058).
The method to get PDFs to work for <object> and <embed> elements requires a script to run on every page. I've profiled the code and found that the impact on performance is negligible, but you still need to be careful if you want to change the logic.
(I first tried to use Mutation Observers for detection, which slowed down the page load by 3-20% on huge documents, and caused an additional 1.5 GB peak in memory usage in a complex DOM benchmark).
The method to detect <object> / <embed> tags might still cause any NPAPI/PPAPI-based PDF plugins to load, because it only replaced the <embed>/<object> tag's content when it has already been inserted and rendered. When a tab is inactive, animations are not scheduled, and hence the dispatch of the animation event will significantly be delayed.
Afterword
PDF.js is open-source, you can view the code for the Chrome extension at https://github.com/mozilla/pdf.js/tree/master/extensions/chromium. If you browse the source, you'll notice that the code is a bit more complex than I explained here. That's because extensions cannot redirect requests at the onHeadersReceived event until I implemented it a few months ago (crbug.com/280464, Chrome 35).
And there is also some logic to make the URL in the omnibox look a bit better.
The PDF.js extension continues to evolve, so unless you want to significantly change the UI of the PDF Viewer, I suggest to ask users to install the PDF.js's official PDF Viewer in the Chrome Web Store, and/or open issues on PDF.js's issue tracker for reasonable feature requests.

Custom PDF Viewer
Basically, to accomplish what you want to do you'll need to:
Interject the PDF's URL when it's loaded;
Stop the PDF from loading;
Start your own PDF viewer and load the PDF inside it.
How to
Using the chrome.webRequest API you can easily listen to the web requests made by Chrome, and, more specifically, the ones that are going to load .pdf files. Using the chrome.webRequest.onBeforeRequest event you can listen to all the requests that end with ".pdf" and get the URL of the requested resource.
Create a page, for example display_pdf.html where you will show the PDFs and do whatever you want with them.
In the chrome.webRequest.onBeforeRequest listener, prevent the resource from being loaded returning {redirectUrl: ...} to redirect to your display_pdf.html page.
Pass the PDF's URL to your page. This can be done in several ways, but, for me, the simplest one is to add the encoded PDF URL at the end of your page's url, like an encoded query string, something like display_pdf.html?url=http%3A%2F%2Fwww.example.com%2Fexample.pdf.
Inside the page, get the URL with JavaScript and process and render the PDF with any library you want, like PDF.js.
The code
Following the above steps, your extension will look like this:
<root>/
/background.js
/display_pdf.html
/display_pdf.js
/manifest.json
So, first of all, let's look at the manifest.json file: you will need to declare the permissions for webRequest and webRequestBlocking, so it should look like this:
{
"manifest_version": 2,
"name": "PDF Test",
"version": "0.0.1",
"background": {
"scripts": ["/background.js"]
},
"permissions": ["webRequest", "webRequestBlocking", "<all_urls>"],
}
Then, in your background.js you will listen to the chrome.webRequest.onBeforeRequest event and update the tab which is loading the PDF with the URL of your custom display_pdv.html page, like this:
chrome.webRequest.onBeforeRequest.addListener(function(details) {
var displayURL;
if (/\.pdf$/i.test(details.url)) { // if the resource is a PDF file ends with ".pdf"
displayURL = chrome.runtime.getURL('/display_pdf.html') + '?url=' + encodeURIComponent(details.url);
return {redirectUrl: displayURL};
// stop the request and proceed to your custom display page
}
}, {urls: ['*://*/*.pdf']}, ['blocking']);
And finally, in your display_pdf.js file you will extract the PDF's url from the query string and use it to do whatever you want:
var PDF_URL = decodeURIComponent(location.href.split('?url=')[1]);
// this will be something like http://www.somesite.com/path/to/example.pdf
alert('The PDF url is: ' + PDF_URL);
// do something with the pdf... like processing it with PDF.js
Working Example
A working example of what I said above can be found HERE.
Documentation links
I recommend you to take a look at the official documentation of the above specified APIs, that you can find following these links:
chrome.webRequest API
chrome.webRequest.onBeforeRequest event
chrome.runtime API
chrome.runtime.getURL method

save as dialog box in Firefox

I want to show the Save as dialog box when a user clicks an HTML button.
I am using DOJO and JavaScript.
In IE document.exec comes to rescue but in Firefox one needs to make changes in filesystem to use NSI.
Any idea will be appreciated.

You can force the browser to download some data using a data url:
content = "This is the text for downloading";
window.location.href = "data:application/octet-stream,"+
encodeURIComponent(content);
The main problem with this is that the user will not be able to choose a filename and the generated filename is some random hash. If you don't mind using Flash, you could use Downloadify, this will give you more control over the Save dialog.

Have the HTML button href to a unknown document type. Say FileName.xxxblah.
This will automatically trigger the Save as Dialog.

It's not exactly what you're looking for, but the only reliable way I know of is to create a server side script on the server which will send the correct headers. In PHP this is how you'd do it:
header('Content-type: text/csv');
header('Content-Disposition: attachment; filename="mydocument.csv";' );
header('Content-length: '.(int)strlen($csvData));
print($csvData);
Content-type is the "mime type" of the document, and for compatibility with some browsers it's important this perfectly matches the extension of the filename.
Content-Disposition: attachment instructs the browser to download the page, even if it wouldn't normally do so for that mime-type, and you're able to provide the filename.
Content-length is the size of the download, this is optional but it must be provided if you want the user to see a progress bar for the download.
Some browsers will present a save as dialog, while others will simply save the file to the user's preferred download folder. You don't have much control over which will happen.

Force download through js or query

Is it possible to force a download through JS or Javascript i-e the web page should not open the file in new tab in the browser but to pop up to let the user to choose eith "save as" or open with ???

With the advent of HTML5 you could just use the new property download in the anchor tag.
The code will look something like
<a download="name_of_downloaded_file" href="path/to/the/download/file"> Clicking on this link will force download the file</a>
It works on firefox and chrome latest version. Should I mention that I didn't check it in IE? :P
Edited the download attribute after comment from sstur
https://caniuse.com/#feat=download

dynamic create link and click it with download attribute for force download as file:
var anchor = document.createElement('a');
anchor.href = this.props.download_url;
anchor.target = '_blank';
anchor.download = this.props.file_name;
anchor.click();
Take a notice that i didn't even added it to DOM, so it's fast.
P.S download attribute won't work with IE. But it will just open link in new tab.
http://caniuse.com/#feat=download

You can not force that behavior from JavaScript, the HTTP Headers need to be set on the server side:
Content-disposition=attachment; filename=some.file.name
The way you can solve the problem is to let your AJAX method redirect the user to the URL of the PDF:
location.replace('path/to.pdf');
(The above HTTP headers must be set for the PDF)
Update
At the time of this answer, it wasn't possible. Now it is, scroll down to see the other answer saying so.

No this is not possible with JQuery/JavaScript only.
You will need a server side script which returns you the file with a Content-Type (HTTP Header) which will force the browser to download your requested file. An possible value for Content-Type would be application/force-download.

No, it is not possible and thanks God it isn't. Otherwise I leave you to the imagination of what kind of files could be stored on your computer when you visit a web site without you knowing it.
As #Paul D. White pointed out in the comments section if you want to open the file inline (inside the browser) with the default program associated with it you could have the server send the Content-Disposition HTTP header. For example:
Content-Disposition: inline; filename=foo.pdf