set an onclick event watcher within an onchange event processing possible? - javascript

I saw a post How do I read in a local text file with javascript?
I want to add a button to simulate an upload. So my consideration is set a watcher to onclick in onchange processing, is it possible?
Here is jsfiddle
js
function readMultipleFiles(evt) {
//Retrieve all the files from the FileList object
var files = evt.target.files;
if (files) {
for (var i = 0, f; f = files[i]; i++) {
alert(f);
var r = new FileReader();
r.onload = (function (f) {
return function (e) {
var contents = e.target.result;
alert(contents);
};
})(f);
r.readAsText(f);
}
} else {
alert("Failed to load files");
}
}
document.getElementById('fileinput').addEventListener('change', readMultipleFiles, false);
html
<input type="file" id="fileinput" multiple />

Instead of the change handler, add a button and add a click handler
<input type="file" id="fileinput" multiple />
<button id="read">Read</button>
then
jQuery(function ($) {
function readMultipleFiles(input) {
//Retrieve all the files from the FileList object
var files = input.files;
if (files && files.length) {
for (var i = 0, f; f = files[i]; i++) {
var r = new FileReader();
r.onload = (function (f) {
return function (e) {
var contents = e.target.result;
alert(contents);
};
})(f);
r.readAsText(f);
}
} else {
alert("Failed to load files");
}
}
var fileIn = $('#fileinput')[0];
$('#read').click(function () {
readMultipleFiles(fileIn)
})
})
Demo: Fiddle

Related

Rewriting file reader in javascript

I currently I have this piece of code which was originally a sample code online but edited slightly to fit my needs.
<input type="file" id="files" name="file" />
<span class="readBytesButtons">
<button>display injected files</button>
<span>
<div id="displayedText"></div>
function readBlob(opt_startByte, opt_stopByte) {
var files = document.getElementById('files').files;
console.log(files);
if (!files.length) {
alert('Please select a file!');
return;
}
//var file = files[0];
var reader = new FileReader();
reader.readAsText(files[0], "UTF-8");
reader.onload = function (evt) {
try {
var startWord = "inject";
var endWord = "];";
var injectedFilesString = evt.target.result.slice(evt.target.result.indexOf(startWord), evt.target.result.indexOf(endWord)) + "]";
var injectedFiles = injectedFilesString.split('[')[1].split(']')[0].split(', ');
document.getElementById("displayedText").innerHTML = injectedFiles
; }
catch(err) {
document.getElementById("displayedText").innerHTML = "<span style='color: red; font-weight: bold; font-family: verdana;'>This file does not have any injected files within it.</span>";
}
}
reader.onerror = function (evt) {
alert("error reading file");
}
}
document.querySelector('.readBytesButtons').addEventListener('click', function(evt) {
if (evt.target.tagName.toLowerCase() == 'button') {
var startByte = evt.target.getAttribute('data-startbyte');
var endByte = evt.target.getAttribute('data-endbyte');
readBlob(startByte, endByte);
console.log(files);
}
}, false);
This piece of code currently reads and displays a certain portion of a file which is selected by the file selector tool. How could I change this code so that I don't need the file selector and could print portions of a file using a method such as fileName.injected();
Thanks, let me know if you have any clarifications

clear thumbnail image on uploading new image?

I am uploading multiple images and previewing it by making thumbnails.And when i reupload the images the previous images are alsop there.How can i clear the previous images on uploading the new images .
my html:-
<div>
<input type="file" id="files" multiple name="media" accept="image/*" />
<output id="list"></output>
</div>
my script of making thumbnail image:-
function handleFileSelect(evt) {
var files = evt.target.files; // FileList object
// Loop through the FileList and render image files as thumbnails.
for (var i = 0, validatedfiles,f; f = files[i],validatedfiles = files[i]; i++) {
if (i > 3) {
break;
}
// alert (f.name);
var reader = new FileReader();
var imagearray = [];
imagearray = files[i];
// alert ( imagearray);
// Closure to capture the file information.
reader.onload = (function (theFile) {
return function (e) {
// Render thumbnail.
span.innerHTML = ['<img class="thumbs_image" src="',e.target.result,'" title="', escape (theFile.name), '"/>'].join('');
document.getElementById('list').insertBefore(span, null);
span.children[1].addEventListener("click", function (event) {
span.parentNode.removeChild(span);
})(imagearray);
// Read in the image file as a data URL.
reader.readAsDataURL(imagearray);
}
}
the html :-
<div>
<input type="file" id="files" multiple name="media" accept="image/*" />
<output id="list"></output>
</div>
i will pass the id of output as empty in script:
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, validatedfiles,f; f = files[i],validatedfiles = files[i]; i++) {
$("#list").html("");
if (i > 3) {
break;
}
// alert (f.name);
var reader = new FileReader();
var imagearray = [];
imagearray = files[i];
// alert ( imagearray);
// Closure to capture the file information.
reader.onload = (function (theFile) {
return function (e) {
// Render thumbnail.
span.innerHTML = ['<img class="thumbs_image" src="',e.target.result,'" title="', escape (theFile.name), '"/>'].join('');
document.getElementById('list').insertBefore(span, null);
span.children[1].addEventListener("click", function (event) {
span.parentNode.removeChild(span);
})(imagearray);
// Read in the image file as a data URL.
reader.readAsDataURL(imagearray);
}
}

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">

How to read files from folder

Found this article which showing how to distinguish file upload from directory How to handle dropped folders but they not explain how I can handle the directory upload. Having difficulties to find any example. Anyone know how to get File instance of each file in directory?
Copied from that article:
<div id=”dropzone”></div>
var dropzone = document.getElementById('dropzone');
dropzone.ondrop = function(e) {
var length = e.dataTransfer.items.length;
for (var i = 0; i < length; i++) {
var entry = e.dataTransfer.items[i].webkitGetAsEntry();
if (entry.isFile) {
... // do whatever you want
} else if (entry.isDirectory) {
... // do whatever you want
}
}
};
Use DirectoryReader directoryEntry.createReader() , readEntries() for folders or , FileEntry file() for single or multiple file drops.
html
<div id="dropzone"
ondragenter="event.stopPropagation(); event.preventDefault();"
ondragover="event.stopPropagation(); event.preventDefault();"
ondrop="event.stopPropagation(); event.preventDefault(); handleDrop(event);">
Drop files
</div>
javascript
function handleFiles(file) {
console.log(file);
// do stuff with `File` having `type` including `image`
if (/image/.test(file.type)) {
var img = new Image;
img.onload = function() {
var figure = document.createElement("figure");
var figcaption = document.createElement("figcaption");
figcaption.innerHTML = file.name;
figure.appendChild(figcaption);
figure.appendChild(this);
document.body.appendChild(figure);
URL.revokeObjectURL(url);
}
var url = URL.createObjectURL(file);
img.src = url;
} else {
console.log(file.type)
}
}
function handleDrop(event) {
var dt = event.dataTransfer;
var files = dt.files;
var length = event.dataTransfer.items.length;
for (var i = 0; i < length; i++) {
var entry = dt.items[i].webkitGetAsEntry();
if (entry.isFile) {
// do whatever you want
console.log("isFile", entry.isFile);
entry.file(handleFiles);
} else if (entry.isDirectory) {
// do whatever you want
console.log("isDirectory", entry.isDirectory);
var reader = entry.createReader();
reader.readEntries(function(entries) {
entries.forEach(function(dir, key) {
dir.file(handleFiles);
})
})
}
}
}
plnkr http://plnkr.co/edit/eGAnbA?p=preview
After you drag some file from your disk. This event.dataTransfer.file is your fileList object.
Your could create a formData then
Add files from fileList to formData one by one.
In the end you could submit formData to server with Ajax

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);
};

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