JavaScript file upload size validation
Is there any way to check file size before uploading it using JavaScript?
Yes, you can use the File API for this.
Here's a complete example (see comments):
document.getElementById("btnLoad").addEventListener("click", function showFileSize() {
// (Can't use `typeof FileReader === "function"` because apparently it
// comes back as "object" on some browsers. So just see if it's there
// at all.)
if (!window.FileReader) { // This is VERY unlikely, browser support is near-universal
console.log("The file API isn't supported on this browser yet.");
return;
}
var input = document.getElementById('fileinput');
if (!input.files) { // This is VERY unlikely, browser support is near-universal
console.error("This browser doesn't seem to support the `files` property of file inputs.");
} else if (!input.files[0]) {
addPara("Please select a file before clicking 'Load'");
} else {
var file = input.files[0];
addPara("File " + file.name + " is " + file.size + " bytes in size");
}
});
function addPara(text) {
var p = document.createElement("p");
p.textContent = text;
document.body.appendChild(p);
}
body {
font-family: sans-serif;
}
<form action='#' onsubmit="return false;">
<input type='file' id='fileinput'>
<input type='button' id='btnLoad' value='Load'>
</form>
Slightly off-topic, but: Note that client-side validation is no substitute for server-side validation. Client-side validation is purely to make it possible to provide a nicer user experience. For instance, if you don't allow uploading a file more than 5MB, you could use client-side validation to check that the file the user has chosen isn't more than 5MB in size and give them a nice friendly message if it is (so they don't spend all that time uploading only to get the result thrown away at the server), but you must also enforce that limit at the server, as all client-side limits (and other validations) can be circumvented.
Using jquery:
$('#image-file').on('change', function() {
console.log('This file size is: ' + this.files[0].size / 1024 / 1024 + "MiB");
});
<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.6.0/jquery.min.js"></script>
<form action="upload" enctype="multipart/form-data" method="post">
Upload image:
<input id="image-file" type="file" name="file" />
<input type="submit" value="Upload" />
</form>
Works for Dynamic and Static File Element
Javascript Only Solution
function validateSize(input) {
const fileSize = input.files[0].size / 1024 / 1024; // in MiB
if (fileSize > 2) {
alert('File size exceeds 2 MiB');
// $(file).val(''); //for clearing with Jquery
} else {
// Proceed further
}
}
<input onchange="validateSize(this)" type="file">
It's pretty simple.
const oFile = document.getElementById("fileUpload").files[0]; // <input type="file" id="fileUpload" accept=".jpg,.png,.gif,.jpeg"/>
if (oFile.size > 2097152) // 2 MiB for bytes.
{
alert("File size must under 2MiB!");
return;
}
No Yes, using the File API in newer browsers. See TJ's answer for details.
If you need to support older browsers as well, you will have to use a Flash-based uploader like SWFUpload or Uploadify to do this.
The SWFUpload Features Demo shows how the file_size_limit
setting works.
Note that this (obviously) needs Flash, plus the way it works is a bit different from normal upload forms.
If you're using jQuery Validation, you could write something like this:
$.validator.addMethod(
"maxfilesize",
function (value, element) {
if (this.optional(element) || ! element.files || ! element.files[0]) {
return true;
} else {
return element.files[0].size <= 1024 * 1024 * 2;
}
},
'The file size can not exceed 2MiB.'
);
I made something like that:
$('#image-file').on('change', function() {
var numb = $(this)[0].files[0].size / 1024 / 1024;
numb = numb.toFixed(2);
if (numb > 2) {
alert('to big, maximum is 2MiB. You file size is: ' + numb + ' MiB');
} else {
alert('it okey, your file has ' + numb + 'MiB')
}
});
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.0.0/jquery.min.js"></script>
<input type="file" id="image-file">
Even though the question is answered, I wanted to post my answer. Might come handy to future viewers.You can use it like in the following code.
document.getElementById("fileinput").addEventListener("change",function(evt) {
//Retrieve the first (and only!) File from the FileList object
var f = evt.target.files[0];
if (f) {
var r = new FileReader();
r.onload = function(e) {
var contents = e.target.result;
alert("Got the file\n" +
"name: " + f.name + "\n" +
"type: " + f.type + "\n" +
"size: " + f.size + " bytes\n" +
"starts with: " + contents.substr(1, contents.indexOf("\n"))
);
if (f.size > 5242880) {
alert('File size Greater then 5MiB!');
}
}
r.readAsText(f);
} else {
alert("Failed to load file");
}
})
<input type="file" id="fileinput" />
I use one main Javascript function that I had found at Mozilla Developer Network site https://developer.mozilla.org/en-US/docs/Using_files_from_web_applications, along with another function with AJAX and changed according to my needs. It receives a document element id regarding the place in my html code where I want to write the file size.
<Javascript>
function updateSize(elementId) {
var nBytes = 0,
oFiles = document.getElementById(elementId).files,
nFiles = oFiles.length;
for (var nFileId = 0; nFileId < nFiles; nFileId++) {
nBytes += oFiles[nFileId].size;
}
var sOutput = nBytes + " bytes";
// optional code for multiples approximation
for (var aMultiples = ["K", "M", "G", "T", "P", "E", "Z", "Y"], nMultiple = 0, nApprox = nBytes / 1024; nApprox > 1; nApprox /= 1024, nMultiple++) {
sOutput = " (" + nApprox.toFixed(3) + aMultiples[nMultiple] + ")";
}
return sOutput;
}
</Javascript>
<HTML>
<input type="file" id="inputFileUpload" onchange="uploadFuncWithAJAX(this.value);" size="25">
</HTML>
<Javascript with XMLHttpRequest>
document.getElementById('spanFileSizeText').innerHTML=updateSize("inputFileUpload");
</XMLHttpRequest>
Cheers
JQuery example provided in this thread was extremely outdated, and google wasn't helpful at all so here is my revision:
<script type="text/javascript">
$('#image-file').on('change', function() {
console.log($(this)[0].files[0].name+' file size is: ' + $(this)[0].files[0].size/1024/1024 + 'Mb');
});
</script>
I ran across this question, and the one line of code I needed was hiding in big blocks of code.
Short answer: this.files[0].size
By the way, no JQuery needed.
You can try this fineuploader
It works fine under IE6(and above), Chrome or Firefox
I use this script to validate file type and size
var _validFilejpeg = [".jpeg", ".jpg", ".bmp", ".pdf"];
function validateForSize(oInput, minSize, maxSizejpeg) {
//if there is a need of specifying any other type, just add that particular type in var _validFilejpeg
if (oInput.type == "file") {
var sFileName = oInput.value;
if (sFileName.length > 0) {
var blnValid = false;
for (var j = 0; j < _validFilejpeg.length; j++) {
var sCurExtension = _validFilejpeg[j];
if (sFileName.substr(sFileName.length - sCurExtension.length, sCurExtension.length)
.toLowerCase() == sCurExtension.toLowerCase()) {
blnValid = true;
break;
}
}
if (!blnValid) {
alert("Sorry, this file is invalid, allowed extension is: " + _validFilejpeg.join(", "));
oInput.value = "";
return false;
}
}
}
fileSizeValidatejpeg(oInput, minSize, maxSizejpeg);
}
function fileSizeValidatejpeg(fdata, minSize, maxSizejpeg) {
if (fdata.files && fdata.files[0]) {
var fsize = fdata.files[0].size /1024; //The files property of an input element returns a FileList. fdata is an input element,fdata.files[0] returns a File object at the index 0.
//alert(fsize)
if (fsize > maxSizejpeg || fsize < minSize) {
alert('This file size is: ' + fsize.toFixed(2) +
"KB. Files should be in " + (minSize) + " to " + (maxSizejpeg) + " KB ");
fdata.value = ""; //so that the file name is not displayed on the side of the choose file button
return false;
} else {
console.log("");
}
}
}
<input type="file" onchange="validateForSize(this,10,5000);" >
If you set the Ie 'Document Mode' to 'Standards' you can use the simple javascript 'size' method to get the uploaded file's size.
Set the Ie 'Document Mode' to 'Standards':
<meta http-equiv="X-UA-Compatible" content="IE=Edge">
Than, use the 'size' javascript method to get the uploaded file's size:
<script type="text/javascript">
var uploadedFile = document.getElementById('imageUpload');
var fileSize = uploadedFile.files[0].size;
alert(fileSize);
</script>
It works for me.
Simple way is
const myFile = document.getElementById("fileUpload").files[0];
if (myFIle.size > 2097152) // 2 MiB for bytes.
{
alert("File size must under 2MiB!");
return;
}
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