I was wondering if it is possible to store the image from
<input type="file" id="image">
locally. Would I have to store the image, or could I simply store the image location?
For context, it's from a form that takes name, address etc from input forms, creates an object, stores it in an array and displays the array.
Contrary to the other answers here, if you're using a modern browser you can get and store quite a bit about the contents of a file <input> using elm.files, FileReader and window.localStorage. You can even tell the browser to save it again (default download behaviour).
It should be noted that doing this does not mean you can set the .value on the <input> node.
Here is an example of what you can do, assuming a file has been chosen.
// From <input> node
var elm = document.getElementById('image'),
img = elm.files[0],
fileName = img.name, // not path
fileSize = img.size; // bytes
// By Parsing File
var reader = new FileReader(),
binary, base64;
reader.addEventListener('loadend', function () {
binary = reader.result; // binary data (stored as string), unsafe for most actions
base64 = btoa(binary); // base64 data, safer but takes up more memory
}, false);
reader.readAsBinaryString(img);
From here you can save in localStorage, create dataURIs etc. For example, Say from fileName we know the image is a .jpg, then you could display it by setting an <img>'s src to "data:image/jpeg;base64," + base64.
Note that any modification of this data will not have any effect on the original file chosen.
No way. But if you could that would raise serious security issues.
If you try to get value of your file input e.g.:
document.getElementById('image').value
the value would be "C:\fakepath\somefile.txt"
No. Since storing a file or accessing a file on the local OS would violate the permissions of the browser. So your scripts cannot access the content unless it has been uploaded to the server. Also different browsers handle the path of the file that has been selected in different ways. So you encounter a number of problems there.
That said, there are some ways to get around this that I will not discuss. Simply put, the image should be uploaded to the server in some fashion and then your scripts can reference the path or the image itself from the path that it was uploaded to.
If you want to get the file name, or even display the image, you can do that using the File API (on browsers that support it). The path is not available for security reasons.
Related
I am trying to build a webpage that will use an HTML form to upload an image file. Once uploaded, my goal is to convert this image to a favicon, and make it the favicon of the current page. Is there a way to use vanilla JavaScript to achieve this?
If converting to an image to a favicon is not possible with JavaScript on its own, would it be possible to upload a ".ico" file instead, and make it the favicon of the current page?
Vanilla JavaScript is a term used to mean "JavaScript + APIs provided by web browsers", so it can't do the upload part.
You can read the file with a FileReader, and then assign the resulting data: scheme URL as the favicon.
Note that this demo will run, but you won't see the result because the favicon is set on a document loaded inside a frame and not on the SO page it runs in.
document.querySelector('input').addEventListener('change', e => {
const { files } = e.target;
const reader = new FileReader();
reader.addEventListener('load', e => {
const url = reader.result;
console.log(url); // For the sake of this demo
document.querySelector('link[rel=icon]').href = url;
});
// This would benefit from error handling in case a file wasn't selected or it wasn't an image
reader.readAsDataURL(files[0]);
});
<link rel="icon">
<input type=file>
Obviously, this won't persist unless you do something to make it persist (like storing it in local storage and then checking to see if an image is stored there when the page is loaded again.
If you want to upload it then you'll need to send the data to the server. The easiest way to do that is to just have a regular form submission, but you could also use Ajax.
Then you'll need code to store it on the server and add it to the webpage next time someone requests it. The specifics of that really depend on you existing server-side environment.
I want to load an image file from the computer directly to any js object without using any server-side component. For example, I want to select a picture from the local machine and display it on a webpage. Is there a way to avoid file upload to the server?
In fact I want to write a kind of multiple image loader, but before loading to the server I want to rotate some images, create an xml-file with some data like user id, image file names list and to zip all images and this xml and then send it to the server. How can I do that on the client side?
There is a way with HTML5, but it requires the user to have dropped the file into a drop target or used a <input type="file"/> box, since otherwise it would be a security issue.
Using the File API you can read files, and specifically you can use the FileReader.readAsDataURL method to set the content as a data: URL for the image tag.
Here's an example:
$('#f').on('change', function(ev) {
var f = ev.target.files[0];
var fr = new FileReader();
fr.onload = function(ev2) {
console.dir(ev2);
$('#i').attr('src', ev2.target.result);
};
fr.readAsDataURL(f);
});
http://jsfiddle.net/alnitak/Qszjg/
Using the new File APIs, it is possible to access content from the local disk.
You put a traditional <input type="file"> upload field on your page, and handle the onchange event.
MDN has a good writeup with all of the details.
Your event handler gets a FileList containing Files. From there, you can call FileReader.readAsDataURL(File) to fetch the content of the image and then pass that data URL to an <img> or a <canvas> to do rotation.
You can use createObjectURL method of the window.URL object, this doesn't have much browser support though
http://jsfiddle.net/LvAqp/ only works in chrome and firefox
I'm making an application in HTML5 where you choose a video file, and then the application plays it with the HTML5 video tag and the window.URL.createObjectURL(). The problem is that I want to save the data about this video in localStorage and play it again when the user uses my application, but as Mozilla MDN states about the results of this method:
Browsers will release these automatically when the document is unloaded
So is it possible to do what I'm trying to do? Or do the same thing without the window.URL.createObjectURL() but with something else?
I haven't used createObjectURL(), but if I understand correctly, it's essentially a temporary reference to a file or an in-memory object. If you want to save the actual video, it won't be useful, because the video itself will no longer be referenced by this pointer the next time the user visits the application.
I think you might be able to do this with a data: URL instead, as that URL actually includes the full data from the file. This example demonstrates using a FileReader to generate a data URL. I think you should be able to do this:
var reader = new FileReader();
reader.onload = function(e) {
var myDataUrl = e.target.result;
// do something with the URL in the DOM,
// then save it to local storage
};
reader.readAsDataURL(file);
Update: If you want to go up to 1GB, as you note in your comment, you'd probably be better served by the FileSystem API. This would require you to get the local file, save a copy of the file to persistent filesystem storage, and then use createObjectURL() to get a URL for the file copy. You still have a problem with disk space - you just added 1GB of duplicative file content to the user's filesystem - but I don't think it's possible to keep a persistent reference to a file outside of the browser sandbox otherwise.
I am using an input of type=file and I am trying to figure out how to extract the file location from it. I am using this code:
file = $("#uploadFiles").attr("files")[0];
var fileName = file.fileName;
var formData = 'uploadFile=' + fileName;
and when i alert formData, it says "uploadFile=temp.jpg"
What I want is the alerted message to be something like:
"uploadFile=C:\user\doug\documents\pictures\temp.jpg"
But I don't know the attribute of the file object to put in for file.fileName
Generally, you can only rely on the filename being accessible - used mainly as a preliminary extension checking (e.g. (jpe?g|png|gif)$) on the client side (which only serves to benefit the user, to stop them from uploading a 5mb file that will be not validate on the server anyway).
You can access whatever the browser will give you with...
jQuery
$('file[type=input]').val();
JavaScript
document.getElementById('file-input').value;
For security reasons, this is completely impossible in modern browsers.
When a user is uploading an image, is there a way I can load the image client side and show it to them first, before uploading it to the server? Preferably using javascript/jquery only, but using flash would be acceptable too.
It is possible with the new FileReader interface defined in HTML5 and works on Firefox currently.
A file input has an associated files property which tracks the list of files currently selected for that input. To display a file from this list, create a new FileReader object, initialize its onload event handler, and read the file as a data URL.
// get the first file, foo is a file input field
var file = document.getElementById('foo').files[0];
// setup the reader and the load complete callback
var reader = new FileReader();
reader.onload = function(e) {
var image = new Image();
// string representing the image
image.src = e.target.result;
document.body.appendChild(image);
};
// read the file as a data url
reader.readAsDataURL(file);
Once the file is loaded, you will have access to its contents in a data url scheme, for instance:
data:image/jpeg;base64,...aqHI7sNyPGFjdtQvFr/2Q==
Create a new Image and set its src attribute to this data string.
See a working example here. Firefox only.
You can't really do this cross-browser in JavaScript alone due security restrictions that are in place, there are a few flash versions available though, here's one example (the free version does what you're after).
There are probably more free flash versions out there as well.
Since HTML 5 those things are possible, thanks to the File Object, File Reader and the ´files´ property of the input element.
See here for more information: http://demos.hacks.mozilla.org/openweb/ & http://hacks.mozilla.org/2009/12/file-drag-and-drop-in-firefox-3-6/.
Example (only for demonstration, requires FF 3.5+):
See here: http://gist.github.com/536024
In case you wonder, File.url is brand new, with it you dont anymore need to read the whole file into the memory, and assign the whole DataUrl (data:image/src,base64;DF15EDFE86..) to the src property.
Well, the <img> tag needs a path to the image. That path can be to something on the web, or to a local file. So far, so good. The trick is, how do you tell your javascript the path on the local system, so it can set the IMG SRC attribute.
The path of the file <input> tag is unavailable to javascript (as a security precaution --- you don't want a want page upload files from you system behind your back).
On the other hand, if you can get your users to enter a correct file path name into a text <input> field, then it should be possible.