Develop Reference

How to get all url's image from a multiple input file?

I'm trying to get all url values from a multiple input file. It works correctly with just one image but if I try to attach more than one, I retrieve a null response and only get the last one correctly. I hope anybody could help with this issue!
Post my code below and JSFiddle example:
<input type="file" id="files" name="files[]" multiple />
<output id="list"></output>
<script>
function handleFileSelect(evt) {
var files = evt.target.files; // FileList object
// Loop through the FileList and render image files as thumbnails.
for (var i = 0, f; f = files[i]; i++) {
// Only process image files.
if (!f.type.match('image.*')) {
continue;
}
var reader = new FileReader();
// Closure to capture the file information.
reader.onload = (function(theFile) {
return function(e) {
//show url image
var dataURL = reader.result;
alert(dataURL);
};
})(f);
// Read in the image file as a data URL.
reader.readAsDataURL(f);
}
}
document.getElementById('files').addEventListener('change', handleFileSelect, false);
</script>
https://jsfiddle.net/3q49moyj/

Using the FileReader API

I am trying to read a local static file using the FileReader API but for some reason it's not reading anything. I am using:
var file = new File(
[""],
"config.toml"
);
var reader = new FileReader();
reader.onload = event => {
console.log(reader.result);
};
reader.readAsText(file);
The result is just empty. What am I doing wrong? Also, how will Javascript know where to look for config.toml?
EDIT: To clarify, I want to read the file from the server where the application is hosted not from the client machine.

In your code you are using File constructor which returns a newly constructed File, where the arguments are as follows:
var myFile = new File(bits, name[, options]);
bits An Array of ArrayBuffer, ArrayBufferView, Blob, or DOMString objects — or a mix of any such objects. This is the file content encoded as UTF-8
name A USVString representing the file name or the path to the file
It does read the file from the path you supply. So it will read the content you've passed to it, and you've passed to it an empty string.
If you want to read a file from file system you will need to use an input element with type attribute set to file and browse for it.
Here is an sample how to use the FileReader api to read images:
function handleFileSelect(evt) {
var files = evt.target.files;
// Loop through the FileList and render image files as thumbnails.
for (var i = 0, f; f = files[i]; i++) {
// Only process image files.
if (!f.type.match('image.*')) {
continue;
}
var reader = new FileReader();
// Closure to capture the file information.
reader.onload = (function(theFile) {
return function(e) {
// Render thumbnail.
var span = document.createElement('span');
span.innerHTML = [
'<img class="thumb" src="',
e.target.result,
'" title="',
escape(theFile.name),
'"/>'
].join('');
document.getElementById('list').insertBefore(span, null);
};
})(f);
// Read in the image file as a data URL.
reader.readAsDataURL(f);
}
}
document.getElementById('files').addEventListener('change', handleFileSelect, false);
.thumb {
height: 75px;
border: 1px solid #000;
margin: 10px 5px 0 0;
}
<input type="file" id="files" name="files[]" multiple />
<output id="list"></output>

Reading local file using JavaScript

So i have a file locally called "index.html" which i access using the "file://" protocol. (So not the "http://" protocol). I need to access a file "data.txt" in the same directory which is continuously changed by a seperate program, but since i'm using the file protocol the access to the file is denied for security reasons.
What could i do to read the local file? I thought of running a local server using XAMPP or WAMP but i'd rather not use any extra programs.
EDIT:
I cannot use an input file, since it should work without any user interaction.

You may do it via the File API - https://www.w3.org/TR/file-upload/
The example below filters out images from the user's selection, calls reader.readAsDataURL() on the file, and renders a thumbnail by setting the 'src' attribute to a data URL.
<style>
.thumb {
height: 75px;
border: 1px solid #000;
margin: 10px 5px 0 0;
}
</style>
<input type="file" id="files" name="files[]" multiple />
<output id="list"></output>
<script>
function handleFileSelect(evt) {
var files = evt.target.files; // FileList object
// Loop through the FileList and render image files as thumbnails.
for (var i = 0, f; f = files[i]; i++) {
// Only process image files.
if (!f.type.match('image.*')) {
continue;
}
var reader = new FileReader();
// Closure to capture the file information.
reader.onload = (function(theFile) {
return function(e) {
// Render thumbnail.
var span = document.createElement('span');
span.innerHTML = ['<img class="thumb" src="', e.target.result,
'" title="', escape(theFile.name), '"/>'].join('');
document.getElementById('list').insertBefore(span, null);
};
})(f);
// Read in the image file as a data URL.
reader.readAsDataURL(f);
}
}
document.getElementById('files').addEventListener('change', handleFileSelect, false);
</script>

angularjs preview multiple image image on upload

I am trying to create a product upload form in which I have to upload multiple images and show previews. So far I can upload one image but don't know how to upload multiple images with preview. I am uploading the form through form data.
HTML
Select image
Change
Remove

See the article: http://www.html5rocks.com/en/tutorials/file/dndfiles/
<style>
.thumb {
height: 75px;
border: 1px solid #000;
margin: 10px 5px 0 0;
}
</style>
<input type="file" id="files" name="files[]" multiple />
<output id="list"></output>
<script>
function handleFileSelect(evt) {
var files = evt.target.files; // FileList object
// Loop through the FileList and render image files as thumbnails.
for (var i = 0, f; f = files[i]; i++) {
// Only process image files.
if (!f.type.match('image.*')) {
continue;
}
var reader = new FileReader();
// Closure to capture the file information.
reader.onload = (function(theFile) {
return function(e) {
// Render thumbnail.
var span = document.createElement('span');
span.innerHTML = ['<img class="thumb" src="', e.target.result,
'" title="', escape(theFile.name), '"/>'].join('');
document.getElementById('list').insertBefore(span, null);
};
})(f);
// Read in the image file as a data URL.
reader.readAsDataURL(f);
}
}
document.getElementById('files').addEventListener('change', handleFileSelect, false);
</script>

read in a file from url or filesystem to variable in javascript

I am trying to read in a file from a file on my computer and store in in a variable.
I am currently trying:
var fr = new FileReader;
fr.onload = function() {
//variable to hold file
var data = fr.result;
var c=document.getElementById("cvs");
var ctx=c.getContext("2d");
ctx.drawImage(img,0,0,200,180);
};
fr.readAsDataURL("encryptedImage");
this does not work. I need to do this do i can decrypt an encrypted image on my file system. I have already turned of the security so my file system can be read from a browser.
any ideas?

From here it looks like you want to load the local file by passing a String to readAsArrayBuffer(), but it exspects a blob or file object. The file can be loaded via the browsers file dialog.
Steps are : Select the file, load the file via fileReader asArrayBuffer or asDataURL or asBinaryString ... and manipulate or use the data in your code.
For this example it creates an Image from the local file and draws it onto the canvas (if it's of correct mime type "image.*" however).
I'm not sure what kind of encoding/decoding you want to apply. But for custom manipulation of data I would recommend using ArrayBuffers and TypeArrays.
The example with FileReader.readAsDataURL(): http://jsfiddle.net/uvmD7/
<body>
<canvas id="cvs" width="200" height="200"></canvas>
<input type="file" id="files" name="files[]" multiple />
</body>
And the script:
document.getElementById('files').addEventListener('change', handleFileSelect, false);
var fr = new FileReader();
function handleFileSelect(evt) {
var files = evt.target.files;
fr.readAsDataURL(files[0]);
};
fr.onload = function(evt) {
// do sth with it
var data = evt.target.result; //fr.result
img = new Image();
img.src = data;
// draw after load
img.onload = function() {
var c=document.getElementById("cvs");
var ctx=c.getContext("2d");
ctx.drawImage(img,0,0,200,180);
};
};