We Keep Coding

Add style to a javascript variable

I got this code from a website and applied to my code:
window.onload = function () {
var fileUpload = document.getElementById("fileupload");
fileUpload.onchange = function () {
if (typeof (FileReader) != "undefined") {
var dvPreview = document.getElementById("dvpreview");
dvPreview.innerHTML = "";
var regex = /^([a-zA-Z0-9\s_\\.\-:])+(.jpg|.jpeg|.gif|.png)$/;
for (var i = 0; i < fileUpload.files.length; i++) {
var file = fileUpload.files[i];
if (regex.test(file.name.toLowerCase())) {
var reader = new FileReader();
reader.onload = function (e) {
var img = document.createElement("IMG");
img.width="300";
img.height ="300";
img.src = e.target.result;
dvPreview.appendChild(img);
}
reader.readAsDataURL(file);
} else {
alert(file.name + " is not a valid image file.");
dvPreview.innerHTML = "";
return false;
}
}
}
}
};
It works properly, but I want some more style to be added to my code. Specially the padding and the object-fit css properties.
I tried to run:
img.objectFit="cover";
img.style.objectFit="cover";
img.css("object-fit","cover");
and a lot more possibilities that i could search and apply, but any of those worked out.
What is the right way to make this work?

var img = document.createElement('img');
img.width = '300';
img.height = '300';
img.style.padding = '20px';
img.style.objectFit = 'fill';
document.body.appendChild(img);

Why is my function only applying SRC property only to the first uploaded image?

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);
});
}

Preview images before upload

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">

Send default image with ajax

Hi guys how can i convert a image to object in this code for example:
var img = $('<img id="dynamic">');
img.attr('src', 'http://macreationdentreprise.fr/wp-content/uploads/2012/06/ouvrir-un-restaurant.jpeg');
var obj=img.ConvertToObject();
// so i can now use obj.filename; and obj.data;
The reason to do that is if i wan't to upload this image automatically if the input file isn't set:
<input id="picture_zone_upload_input_ID" type="file" name="picture_zone_upload_input" class="picture_zone_upload_input" multiple title="Choose a file to upload"/>
EDIT
function configure_zone_upload() {
$("#picture_zone_upload_input_ID").change(function (event) {
$.each(event.target.files, function (index, file) {
var reader = new FileReader();
reader.onload = function (event) {
object = {};
object.filename = file.name;
object.data = event.target.result;
//alert("index: " + index);
upload_img_count++;
configure_upload_img(object.data, upload_img_count);
files.push(object);
};
reader.readAsDataURL(file);
});
var files = event.target.files;
for (var x = 0; x < files.length; x++) {
data.append(x, files[x]);
}
//alert(files.length);
AJAX_upload_Profile(data, upload_img_count);
});
}
If there isn't a input file how can i set the my default image to send it with ajax ??
EDIT2
If event.target.files; is null how can i set file from new image:
var files = event.target.files;
for (var x = 0; x < files.length; x++) {
data.append(x, files[x]);
}
//alert(files.length);
AJAX_upload_Profile(data, upload_img_count);

I guess you can do this:
object.filename = file.name || defaultImg;
where defaultImg is a variable which contains a default img with src.
somthing like:
reader.onload = function (event) {
object = {};
object.defaultImg = $('<img>',{"src" : "defaultImg/path/img.jpeg"}); // <--declare here
object.filename = file.name
object.data = event.target.result || object.defaultImg; //<---use it here;
//alert("index: " + index);
upload_img_count++;
configure_upload_img(object.data, upload_img_count);
files.push(object);
};

How to make a list of image preview

I have the following code for image preview
$("#weeklyOfferImages").change(function(){
readURLWeekly(this);
});
function readURLWeekly(input) {
if (input.files && input.files[0]) {
var reader = new FileReader();
reader.onload = function (e) {
$('.weeklyPreview').append('<img data-src="holder.js/140x140" src="'+e.target.result'"class="offer-image img-polaroid"/>');
},
reader.readAsDataURL(input.files[0]);
}
}
this code only display one image at a time.
How can i make it display multiple images. for example the files object contains 4 files.

you only display "0" -> img input.files[0]
dynamic with length - iterating the whole array
function readURLWeekly(input) {
if(input.files)
for(var i = 0; i < input.files.length; i++) {
if (input.files[i]) {
var reader = new FileReader();
reader.onload = function(e) {
$('.weeklyPreview').append('<img data-src="holder.js/140x140" src="' + e.target.result + '" class="offer-image img-polaroid"/>');
},
reader.readAsDataURL(input.files[i]);
}
}
}

Maybe something like this :
$("#weeklyOfferImages").change(function(){
readURLWeekly(this);
});
function readURLWeekly(input) {
if (input.files) {
for (var i=0;i<4;i++) {
if (input.files[i]) {
var reader = new FileReader();
reader.onload = function (e) {
$('.weeklyPreview').append('<img data-src="holder.js/140x140" src="'+e.target.result'"class="offer-image img-polaroid"/>');
},
reader.readAsDataURL(input.files[i]);
} else {
break;
}
}
}
}