The function successfully creates N image elements with a class of new-avatar-picture, however, it only adds SRC property to the first image. I'm not getting any errors in the console either.
function displayInputImage(input) {
var files = input.files;
for (var i = 0; i < files.length; i++) {
var file = files[i];
var reader = new FileReader();
var x = document.createElement("img");
reader.onload = function(e) {
x.setAttribute("src", e.target.result);
}
reader.readAsDataURL(file);
x.className = "new-avatar-picture";
$('.upload-btn-wrapper').append(x);
}
}
The issue with your logic is due to the fact that onload() of the reader fires after the loop completes, so x will refer to the last element in the set. Hence that single element gets its src set N times.
To fix this you could use a closure:
function displayInputImage(input) {
for (var i = 0; i < input.files.length; i++) {
var $img = $("<img />");
(function($imgElement) {
var reader = new FileReader();
reader.onload = function(e) {
$imgElement.prop("src", e.target.result);
}
reader.readAsDataURL(input.files[i]);
$imgElement.addClass("new-avatar-picture");
$('.upload-btn-wrapper').append($imgElement);
}($img));
}
}
Alternatively you could create the new img elements only after the content of the file is read:
function displayInputImage(input) {
for (var i = 0; i < input.files.length; i++) {
var reader = new FileReader();
reader.onload = function(e) {
$('<img />').addClass('new-avatar-picture').prop('src', e.target.result).appendTo('.upload-btn-wrapper');
}
reader.readAsDataURL(input.files[i]);
}
}
One way to do that is to give each image a new property, I call it temp_src so that the browser will not try to load the images right away.
Then in the .onload event, loop through all images that you have created and give each of them the proper src value, by copying it from its temp_src property.
Something like:
var reader = new FileReader();
function displayInputImage(input) {
var files = input.files;
for (var i = 0; i < files.length; i++) {
var file = files[i];
var x = document.createElement("img");
x.setAttribute("class", "temp_img");
x.setAttribute("temp_src", file);
reader.readAsDataURL(file);
x.className = "new-avatar-picture";
$('.upload-btn-wrapper').append(x);
}
}
reader.onload = function(e) {
var images = document.getElementsByClassName("tmp_img");
images.forEach(function(img) {
img.setAttribute("src", img.temp_src);
});
}
Hello I have the following code
function fileValidation() {
var fileInput = document.getElementById('filech');
var filePath = fileInput.value;
var allowedExtensions = /(\.jpg|\.jpeg|\.png|\.gif)$/i;
if (!allowedExtensions.exec(filePath)) {
alert('error .jpeg/.jpg/.png/.gif ');
fileInput.value = '';
return false;
} else {
//Image preview
if (fileInput.files && fileInput.files[0]) {
var reader = new FileReader();
reader.onload = function(e) {
document.getElementById('imagePreview').innerHTML = '<img src="' + e.target.result + '"/>';
};
reader.readAsDataURL(fileInput.files[0]);
}
}
}
<input id="filech" type="file" name="file_img[]" multiple onchange="return fileValidation()" />
<div id="imagePreview"></div>
To upload photos by
<input id="filech" type="file" name="file_img[]" multiple onchange="return fileValidation()" />
then show
<div id="imagePreview"></div>
I want to show all the pictures and not one
How to use the loop here and thank all
Well as you said you will need a loop, the easiest way would be to use a for loop, like this:
for (var i = 0; i < fileInput.files.length; i++) {
if (fileInput.files && fileInput.files[i]) {
var reader = new FileReader();
reader.onload = function(e) {
document.getElementById('imagePreview').innerHTML += '<img src="' + e.target.result + '"/>';
};
reader.readAsDataURL(fileInput.files[i]);
}
}
Note:
Note that I changed it to document.getElementById('imagePreview').innerHTML +=, so it keep printing all the iterated images, otherwise it will just override the preview with the last image content.
But the best practice is to create an img element on each iteration and append it to the preview div:
for (var i = 0; i < fileInput.files.length; i++) {
if (fileInput.files && fileInput.files[i]) {
var reader = new FileReader();
reader.onload = function(e) {
var img = document.createElement("img");
img.src = e.target.result;
document.getElementById('imagePreview').appendChild(img);
};
reader.readAsDataURL(fileInput.files[i]);
}
}
Demo:
function fileValidation() {
var fileInput = document.getElementById('filech');
var filePath = fileInput.value;
var allowedExtensions = /(\.jpg|\.jpeg|\.png|\.gif)$/i;
if (!allowedExtensions.exec(filePath)) {
alert('error .jpeg/.jpg/.png/.gif ');
fileInput.value = '';
return false;
} else {
//Image preview
for (var i = 0; i < fileInput.files.length; i++) {
if (fileInput.files && fileInput.files[i]) {
var reader = new FileReader();
reader.onload = function(e) {
var img = document.createElement("img");
img.src = e.target.result;
document.getElementById('imagePreview').appendChild(img);
};
reader.readAsDataURL(fileInput.files[i]);
}
}
}
}
<input id="filech" type="file" name="file_img[]" multiple onchange="return fileValidation()" />
<div id="imagePreview"></div>
I have a page with four images for the user to select. I want the user to be able to preview each image on the site before upload.
The JavaScript code below works for only one image but I would like it to work for multiple images uploaded via <input type="file">.
What will be the best way to do this?
function readURL(input) {
if (input.files && input.files[0]) {
var reader = new FileReader();
reader.onload = function (e) {
$('#output').attr('src', e.target.result);
}
reader.readAsDataURL(input.files[0]);
}
}
$("#file-input").change(function () {
readURL(this);
});
Here is jQuery version for you. I think it more simplest thing.
$(function() {
// Multiple images preview in browser
var imagesPreview = function(input, placeToInsertImagePreview) {
if (input.files) {
var filesAmount = input.files.length;
for (i = 0; i < filesAmount; i++) {
var reader = new FileReader();
reader.onload = function(event) {
$($.parseHTML('<img>')).attr('src', event.target.result).appendTo(placeToInsertImagePreview);
}
reader.readAsDataURL(input.files[i]);
}
}
};
$('#gallery-photo-add').on('change', function() {
imagesPreview(this, 'div.gallery');
});
});
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<input type="file" multiple id="gallery-photo-add">
<div class="gallery"></div>
Add the multiple attribute to your HTMLInputElement
Add the accept attribute to your HTMLInputElement
To filter your files selection to images only, use accept="image/*", or a comma separated MIME list: accept="image/png, image/jpeg"
Use FileReader.readAsDataURL to get the Base64 string,
or URL.createObjectURL to get the file Blob object
Using FileReader.readAsDataURL
The asynchronous way to read the image data is by using FileReader API and its readAsDataURL method which returns a Base64 String:
const preview = (file) => {
const fr = new FileReader();
fr.onload = () => {
const img = document.createElement("img");
img.src = fr.result; // String Base64
img.alt = file.name;
document.querySelector('#preview').append(img);
};
fr.readAsDataURL(file);
};
document.querySelector("#files").addEventListener("change", (ev) => {
if (!ev.target.files) return; // Do nothing.
[...ev.target.files].forEach(preview);
});
#preview img { max-height: 100px; }
<input id="files" type="file" accept="image/*" multiple>
<div id="preview"></div>
Async strategy:
Due to the asynchronous nature of FileReader, you could implement an async/await strategy:
// DOM utility functions:
const el = (sel, par) => (par || document).querySelector(sel);
const elNew = (tag, props) => Object.assign(document.createElement(tag), props);
// Preview images before upload:
const elFiles = el("#files");
const elPreview = el("#preview");
const previewImage = (props) => elPreview.append(elNew("img", props));
const reader = (file, method = "readAsDataURL") => new Promise((resolve, reject) => {
const fr = new FileReader();
fr.onload = () => resolve({ file, result: fr.result });
fr.onerror = (err) => reject(err);
fr[method](file);
});
const previewImages = async(files) => {
// Remove existing preview images
elPreview.innerHTML = "";
let filesData = [];
try {
// Read all files. Return Array of Promises
const readerPromises = files.map((file) => reader(file));
filesData = await Promise.all(readerPromises);
} catch (err) {
// Notify the user that something went wrong.
elPreview.textContent = "An error occurred while loading images. Try again.";
// In this specific case Promise.all() might be preferred over
// Promise.allSettled(), since it isn't trivial to modify a FileList
// to a subset of files of what the user initially selected.
// Therefore, let's just stash the entire operation.
console.error(err);
return; // Exit function here.
}
// All OK. Preview images:
filesData.forEach(data => {
previewImage({
src: data.result, // Base64 String
alt: data.file.name // File.name String
});
});
};
elFiles.addEventListener("change", (ev) => {
if (!ev.currentTarget.files) return; // Do nothing.
previewImages([...ev.currentTarget.files]);
});
#preview img { max-height: 100px; }
<input id="files" type="file" accept="image/*" multiple>
<div id="preview"></div>
Using URL.createObjectURL
The synchronous way to read the image is by using the URL API and its createObjectURL method which returns a Blob:
const preview = (file) => {
const img = document.createElement("img");
img.src = URL.createObjectURL(file); // Object Blob
img.alt = file.name;
document.querySelector('#preview').append(img);
};
document.querySelector("#files").addEventListener("change", (ev) => {
if (!ev.target.files) return; // Do nothing.
[...ev.target.files].forEach(preview);
});
#preview img { max-height: 120px; }
<input id="files" type="file" accept="image/*" multiple>
<div id="preview"></div>
Although looks much simpler, it has implications on the main thread due to its synchronicity, and requires you to manually use (when possible) URL.revokeObjectURL in order to free up memory:
// Remove unused images from #preview? Consider also using
URL.revokeObjectURL(someImg.src); // Free up memory space
jQuery example:
A jQuery implementation of the above FileReader.readAsDataURL() example:
const preview = (file) => {
const fr = new FileReader();
fr.onload = (ev) => {
$('#preview').append($("<img>", {src: fr.result, alt: file.name}));
};
fr.readAsDataURL(file);
};
$("#files").on("change", (ev) => {
if (!ev.target.files) return; // Do nothing.
[...ev.target.files].forEach(preview);
});
#preview img { max-height: 120px; }
<input id="files" type="file" accept="image/*" multiple>
<div id="preview"></div>
<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.6.1/jquery.min.js"></script>
Additional read:
File API — Using files from web applications (MDN)
readAsDataURL (MDN)
FileReader result (MDN)
Promise.all() (MDN)
Preview Image, get file size, image height and width before upload
Tips:
Besides using the HTMLInputElement attribute accept, if you want to make sure within JavaScript that a file is-of-type, you could:
if (!/\.(jpe?g|png|gif)$/i.test(file.name)) {
// Not a valid image
}
or like:
if (!/^image\//i.test(file.type)) {
// File is not of type Image
}
function previewMultiple(event){
var saida = document.getElementById("adicionafoto");
var quantos = saida.files.length;
for(i = 0; i < quantos; i++){
var urls = URL.createObjectURL(event.target.files[i]);
document.getElementById("galeria").innerHTML += '<img src="'+urls+'">';
}
}
#galeria{
display: flex;
}
#galeria img{
width: 85px;
height: 85px;
border-radius: 10px;
box-shadow: 0 0 8px rgba(0,0,0,0.2);
opacity: 85%;
}
<input type="file" multiple onchange="previewMultiple(event)" id="adicionafoto">
<div id="galeria">
</div>
Just use FileReader.readAsDataURL()
HTML:
<div id='photos-preview'></div>
<input type="file" id="fileupload" multiple (change)="handleFileInput($event.target.files)" />
JS:
function handleFileInput(fileList: FileList) {
const preview = document.getElementById('photos-preview');
Array.from(fileList).forEach((file: File) => {
const reader = new FileReader();
reader.onload = () => {
var image = new Image();
image.src = String(reader.result);
preview.appendChild(image);
}
reader.readAsDataURL(file);
});
}
DEMO
$(function() {
// Multiple images preview in browser
var imagesPreview = function(input, placeToInsertImagePreview) {
if (input.files) {
var filesAmount = input.files.length;
for (i = 0; i < filesAmount; i++) {
var reader = new FileReader();
reader.onload = function(event) {
$($.parseHTML('<img>')).attr('src', event.target.result).appendTo(placeToInsertImagePreview);
}
reader.readAsDataURL(input.files[i]);
}
}
};
$('#gallery-photo-add').on('change', function() {
imagesPreview(this, 'div.gallery');
});
});
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<input type="file" multiple id="gallery-photo-add">
<div class="gallery"></div>
function previewImages() {
var preview = document.querySelector('#preview');
if (this.files) {
[].forEach.call(this.files, readAndPreview);
}
function readAndPreview(file) {
// Make sure `file.name` matches our extensions criteria
if (!/\.(jpe?g|png|gif)$/i.test(file.name)) {
return alert(file.name + " is not an image");
} // else...
var reader = new FileReader();
reader.addEventListener("load", function() {
var image = new Image();
image.height = 100;
image.title = file.name;
image.src = this.result;
preview.appendChild(image);
});
reader.readAsDataURL(file);
}
}
document.querySelector('#file-input').addEventListener("change", previewImages);
<input id="file-input" type="file" multiple>
<div id="preview"></div>
function previewImages() {
var preview = document.querySelector('#preview');
if (this.files) {
[].forEach.call(this.files, readAndPreview);
}
function readAndPreview(file) {
// Make sure `file.name` matches our extensions criteria
if (!/\.(jpe?g|png|gif)$/i.test(file.name)) {
return alert(file.name + " is not an image");
} // else...
var reader = new FileReader();
reader.addEventListener("load", function() {
var image = new Image();
image.height = 100;
image.title = file.name;
image.src = this.result;
preview.appendChild(image);
});
reader.readAsDataURL(file);
}
}
document.querySelector('#file-input').addEventListener("change", previewImages);
<input id="file-input" type="file" multiple>
<div id="preview"></div>
<script type="text/javascript">
var upcontrol = {
queue : null, // upload queue
now : 0, // current file being uploaded
start : function (files) {
// upcontrol.start() : start upload queue
// WILL ONLY START IF NO EXISTING UPLOAD QUEUE
if (upcontrol.queue==null) {
// VISUAL - DISABLE UPLOAD UNTIL DONE
upcontrol.queue = files;
document.getElementById('uploader').classList.add('disabled');
// PREVIEW UPLOAD IMAGES
upcontrol.preview();*enter code here*
//PROCESS UPLOAD ON CLICK
$('#add_files').on('click', function() {
upcontrol.run();
});
}
},
preview : function() {
//upcontrol.preview() : preview uploading file
if (upcontrol.queue) {
var filesAmount = upcontrol.queue.length;
for (i = 0; i < filesAmount; i++) {
var reader = new FileReader();
reader.onload = function(event) {
var fimg = document.createElement('img')
fimg.src = event.target.result,
fimg.classList = "col-sm-6 col-md-6 col-lg-4 float-left center",
document.getElementById('gallery').appendChild(fimg);
}
reader.readAsDataURL(upcontrol.queue[i]);
}
}
},
run : function () {
// upcontrol.run() : proceed upload file
var xhr = new XMLHttpRequest(),
data = new FormData();
data.append('file-upload', upcontrol.queue[upcontrol.now]);
xhr.open('POST', './lockeroom/func/simple-upload.php', true);
xhr.onload = function (e) {
// SHOW UPLOAD STATUS
var fstat = document.createElement('div'),
txt = upcontrol.queue[upcontrol.now].name + " - ";
if (xhr.readyState === 4) {
if (xhr.status === 200) {
// SERVER RESPONSE
txt += xhr.responseText;
} else {
// ERROR
txt += xhr.statusText;
}
}
fstat.innerHTML = txt;
document.getElementById('upstat').appendChild(fstat);
// UPLOAD NEXT FILE
upcontrol.now++;
if (upcontrol.now < upcontrol.queue.length) {
upcontrol.run();
}
// ALL DONE
else {
upcontrol.now = 0;
upcontrol.queue = null;
document.getElementById('uploader').classList.remove('disabled');
}
};
xhr.send(data);
}
};
window.addEventListener("load", function () {
// IF DRAG-DROP UPLOAD SUPPORTED
if (window.File && window.FileReader && window.FileList && window.Blob) {
/* [THE ELEMENTS] */
var uploader = document.getElementById('uploader');
/* [VISUAL - HIGHLIGHT DROP ZONE ON HOVER] */
uploader.addEventListener("dragenter", function (e) {
e.preventDefault();
e.stopPropagation();
uploader.classList.add('highlight');
});
uploader.addEventListener("dragleave", function (e) {
e.preventDefault();
e.stopPropagation();
uploader.classList.remove('highlight');
});
/* [UPLOAD MECHANICS] */
// STOP THE DEFAULT BROWSER ACTION FROM OPENING THE FILE
uploader.addEventListener("dragover", function (e) {
e.preventDefault();
e.stopPropagation();
});
// ADD OUR OWN UPLOAD ACTION
uploader.addEventListener("drop", function (e) {
e.preventDefault();
e.stopPropagation();
uploader.classList.remove('highlight');
upcontrol.start(e.dataTransfer.files);
});
}
// FALLBACK - HIDE DROP ZONE IF DRAG-DROP UPLOAD NOT SUPPORTED
else {
document.getElementById('uploader').style.display = "none";
}
});
</script>
i used somthing like this and i got the best result and easy to understand.
function appendRows(){
$i++;
var html='';
html+='<div id="remove'+$i+'"><input type="file" name="imagefile[]" accept="image/*" onchange="appendloadFile('+$i+')"><img id="outputshow'+$i+'" height="70px" width="90px"><i onclick="deleteRows('+$i+')" class="fas fa-trash-alt"></i></div>';
$("#appendshow").append(html);
}
function appendloadFile(i){
var appendoutput = document.getElementById('outputshow'+i+'');
appendoutput.src = URL.createObjectURL(event.target.files[0]);
}
https://stackoverflow.com/a/59985954/8784402
ES2017 Way
// convert file to a base64 url
const readURL = file => {
return new Promise((res, rej) => {
const reader = new FileReader();
reader.onload = e => res(e.target.result);
reader.onerror = e => rej(e);
reader.readAsDataURL(file);
});
};
// for demo
const fileInput = document.createElement('input');
fileInput.type = 'file';
const img = document.createElement('img');
img.attributeStyleMap.set('max-width', '320px');
document.body.appendChild(fileInput);
document.body.appendChild(img);
const preview = async event => {
const file = event.target.files[0];
const url = await readURL(file);
img.src = url;
};
fileInput.addEventListener('change', preview);
$(function() {
// Multiple images preview in browser
var imagesPreview = function(input, placeToInsertImagePreview) {
if (input.files) {
var filesAmount = input.files.length;
for (i = 0; i < filesAmount; i++) {
var reader = new FileReader();
reader.onload = function(event) {
$($.parseHTML('<img>')).attr('src', event.target.result).appendTo(placeToInsertImagePreview);
}
reader.readAsDataURL(input.files[i]);
}
}
};
$('#gallery-photo-add').on('change', function() {
imagesPreview(this, 'div.gallery');
});
});
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<input type="file" multiple id="gallery-photo-add">
<div class="gallery">
$(function() {
// Multiple images preview in browser
var imagesPreview = function(input, placeToInsertImagePreview) {
if (input.files) {
var filesAmount = input.files.length;
for (i = 0; i < filesAmount; i++) {
var reader = new FileReader();
reader.onload = function(event) {
$($.parseHTML('<img>')).attr('src', event.target.result).appendTo(placeToInsertImagePreview);
}
reader.readAsDataURL(input.files[i]);
}
}
};
$('#gallery-photo-add').on('change', function() {
imagesPreview(this, 'div.gallery');
});
});
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<input type="file" multiple id="gallery-photo-add">
<div class="gallery">
I'm having trouble with a simple file input.
I'm trying to get the width, height and dataURL of multiple images and save them to global variables, but all that's saved is "undefined".
When I tried to make a "demo-fiddle" the "onchange"-event doesn't even seem to fire.
can anyone help me out?
Here's the code of the demo-fiddle:
var WIDTH = [];
var HEIGHT = [];
var SRC = [];
$(window).load(function()
{
grabData();
displayImgs();
});
function grabData()
{
$("#fileInput").on("change",function(e)
{
var file = e.target.files;
for(var i = 0; i<file.length; i++)
{
var reader= new fileReader();
var img = new Image();
reader.onload = function(e)
{
SRC = e.target.result;
img.onload = function()
{
WIDTH = this.width;
HEIGHT = this.height;
}
}
reader.readAsDataURL(file);
console.log(WIDTH);
}
console.log(WIDTH);
});
}
function displayImgs()
{
/*display images*/
for(var i = 0; i<SRC.length; i++)
{
$("body").append("<img src="+SRC[i]+" width="+WIDTH[i]+" height="+HEIGHT[i]+">");
}
}
try below code, tested in fiddle and working - http://jsfiddle.net/02468Lr9/
var WIDTH = [];
var HEIGHT = [];
var SRC = [];
$(document).ready(function() {
grabData();
;
});
function grabData() {
$("#fileInput").on("change",function(e) {
var file = e.target.files;
for(var i = 0; i<file.length; i++) {
var reader= new FileReader();
var img = new Image();
reader.onload = function(e) {
SRC.push(e.target.result);
img.onload = function() {
alert(this.width);
WIDTH.push(this.width);
HEIGHT.push(this.height);
displayImgs();
}
img.src = e.target.result;
}
reader.readAsDataURL(file[i]);
}
});
}
function displayImgs()
{
/*display images*/
for(var i = 0; i<SRC.length; i++) {
console.log(WIDTH);
$("body").append("<img src="+SRC[i]+" width="+WIDTH[i]+" height="+HEIGHT[i]+">");
}
}
The log result is undefined because you log it outside the onload function, and for that it runs before the images load and the value is still undefined.
So I'm doing a simple multiple image upload script using javascript, but socket.io has to be used in order to get the image into the database. In order to run previews I have been taking event.target.result and putting it as the image src on a div. Is there any way I can store the this in an array for each image so that I can transfer it over the socket, and have it load on the other side? When I try to load it into an array, it's always undefined.
for (var i = 0; file = files[i]; i++) {
name[i] = files[i].name;
// if the file is not an image, continue
if (!file.type.match('image.*')) {
continue;
}
reader = new FileReader();
reader.onload = (function (tFile) {
return function (evt) {
var div = document.createElement('div');
var miniDiv = document.createElement('div');
div.id = "photoDiv";
div.innerHTML = '<img style="width: 120px; height: auto;" src="' + evt.target.result + '" />';
div.className = "photos";
var data = evt.target.result;
picture[i] = data;
document.getElementById('filesInfo').appendChild(div);
document.getElementById('previewDiv').appendChild(document.getElementById('filesInfo'));
};
}(file));
reader.readAsDataURL(file);
}
uploadFiles();
}
Don't make functions within a loop like that, it can lead to unexpected things.
I would suggest using JSHint, it's very helpful.
You made two mistakes:
1) You should pass i variable to your closure together with file.
2) The most important: reader.onload is a function that will be called not immediately, but in some delay, and as a result it will be called after uploadFiles() call. That's why you get an empty picture.
Try to rewrite your code as follows:
var done = 0;
var picture = [];
for (var i = 0; file = files[i]; i++) {
name[i] = files[i].name;
// if the file is not an image, continue
if (!file.type.match('image.*')) {
if (++done === files.length) {
uploadFiles();
}
continue;
}
reader = new FileReader();
reader.onload = (function (tFile, index) {
return function (evt) {
//[...]
picture[index] = data;
//[...]
if (++done === files.length) {
//the last image has been loaded
uploadFiles();
}
};
}(file, i));
reader.readAsDataURL(file);
}