File Reader loop Issue - javascript

readFile : function(files)
{
for(x = 0; x < files.length; x = x + 1) {
var file = files[x];
(function(file){
var reader = new FileReader();
reader.readAsDataURL(file);
reader.onload = function(e) {
console.log(e.target.result);
console.log(file.name);
}
})(file);
}
}
var fileObjects = document.querySelectorAll('input[type=file]'), i;
this.readFile(fileObjects)
getting this error
Failed to execute 'readAsDataURL' on 'FileReader': parameter 1 is not of type 'Blob'.

Related

javascript how can i run 2 file reader methods(readAsArrayBuffer() & readAsDataURL())?

i currently have the ff code my goal is to remove the extra filreader loop? is it possible to maybe chain the readAsArrayBuffer and readAsDataURL or load them both?
var images = [];
var files = dt.files.length;
for (i = 0; i < files; i++) {
var reader = new FileReader();
reader.fileId = i;
reader.onload = function (){
images[this.fileId].is_valid = true / false; // checks mime type
}
reader.readAsArrayBuffer(dt.files[i]);
for (i = 0; i < files; i++) {
var reader = new FileReader();
reader.fileId = i;
reader.onload = function (){
//load image
if(image[i].is_valid){
// do this
}else {
// do this
}
}
reader.readAsDataURL(dt.files[i]);

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);
});
}

I have used Javascript reader.onload = function(e) in apex code and it's not working

I have tried to pass the uploaded files value to apex method but facing some issues in javascript logic.
I have added alert after reader.onload = function(e) but didn't get any alert when I'm hitting this javascript function.
HTML CODE
function SponsorshipLetter() {
var files = document.getElementById('fileUpload');
var appId = getCookie('apex__app');
var fileName = 'Passport';
var reader = new FileReader();
reader.file = files[0];
reader.onload = function(e) {
alert('Hello 1' + document.getElementById('fileUpload').value);
var att = new sforce.SObject("Attachment");
att = fileName;
att.ContentType = this.file.type;
var binary = "";
var bytes = new Uint8Array(e.target.result);
var length = bytes.byteLength;
for (var i = 0; i < length; i++) {
binary += String.fromCharCode(bytes[i]);
}
att.Body = (new sforce.Base64Binary(binary)).toString();
alert('attt');
PAP_Finances.sponsorFileUpload(att.Name, att.Body, att.ContentType, appId,
function(result, event) {
return 'Success';
});
}
reader.readAsDataURL(e.target.files[0]);
}

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);
};

Reading PNG Files from Javascript - the argument is not a blob

Trying to read a .png-File with Javascript FileReader
directoryReader.readEntries(function(entries) {
for (var i=0; i<entries.length; i++) {
var reader = new FileReader();
try {
reader.readAsDataURL(entries[i]);
reader.onload = doOnload(entries[i].name);
}
catch (e) {
alert (e.message);
}
}
});
What I get is
Failed to execute 'readAsDataURL' on 'FileReader': The argument is not a Blob.
What can I do?
Found it myself:
directoryReader.readEntries(function(entries) {
for (var i=0; i<entries.length; i++) {
var reader = new FileReader();
var entry = entries[i];
entry.file(function(file){
reader.readAsDataURL(file);
reader.onload = doOnload(entry.name);
});
}
});

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