Check image type in javascript

image-type

See the file-type module for more file types and a CLI.

Install

Usage

Node.js

import readChunk> from 'read-chunk'; import imageType, minimumBytes> from 'image-type'; const buffer = await readChunk('unicorn.png', length: minimumBytes>); await imageType(buffer); //=> 

Or from a remote location:

import https from 'node:https'; import imageType, minimumBytes> from 'image-type'; const url = 'https://upload.wikimedia.org/wikipedia/en/a/a9/Example.jpg'; https.get(url, response =>  response.on('readable', () =>  (async () =>  const chunk = response.read(minimumBytes); response.destroy(); console.log(await imageType(chunk)); //=>  >)(); >); >);

Browser

const xhr = new XMLHttpRequest(); xhr.open('GET', 'unicorn.png'); xhr.responseType = 'arraybuffer'; xhr.onload = () =>  (async () =>  await imageType(new Uint8Array(this.response)); //=>  >)(); >; xhr.send();

API

imageType(input)

Or undefined when there is no match.

input

It only needs the first minimumBytes amount of bytes.

minimumBytes

The minimum amount of bytes needed to detect a file type. Currently, it’s 4100 bytes, but it can change, so don’t hardcode it.

Supported file types

SVG isn’t included as it requires the whole file to be read, but you can get it here.

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Checking Image Type with JavaScript

One way to identify file types without loading the FileReader is by using a code snippet. This snippet can help identify the mime type of various image formats, such as jpg, gif, and pngs. For more information on how to check file MIME types with JavaScript before uploading, refer to the provided link.

Detect within the browser if the image uploaded is of correct format

It is not secure to determine the mime type solely based on the filename. Instead, the accurate mime type of a file can be obtained by examining the signature bytes located at the start of the file content.

This list provides pairings of signature and mime types for easy reference.

Check if the selected file is a valid jpeg file by examining its signature. The signature of a jpeg file is simple — the file’s first 2 bytes must be 0xFF and 0xD8. For more comprehensive signature information, refer to the list provided.

document.querySelector('input').addEventListener('change', function() < var reader = new FileReader(); reader.onload = function() < var bytes = new Uint8Array(this.result); if ((bytes[0] == 0xFF) && (bytes[1] == 0xD8)) console.log("this is a valid jpeg file"); else console.log("this does not look like a jpeg file"); >reader.readAsArrayBuffer(this.files[0]); >);

Implement the onChange event handler on the input.

Subsequently, incorporate a listener in JavaScript that will detect any alterations made to the input.

const file_input = document.getElementById(("file_uploader") file_input.addEventListener("change", handleChange) 

By passing in event automatically, you can reference it within the handleChange function.

The utilization of the split method will produce an array comprising of two strings. The first string in the array will be the filename that precedes the . while the second string will be the extension that follows the . .

Alper Cinar has cautioned against the potential risks associated with reading file extensions, suggesting instead that we identify mime types by examining the starting bytes of a file. To expand upon this, I will provide a code snippet that can be used to identify the mime types of not only JPEGs, but also PNGs and GIFs.

 const blob = files[0]; const fileReader = new FileReader(); fileReader.readAsArrayBuffer(blob); fileReader.onloadend = (e) => < const arr = (new Uint8Array(e.target.result)).subarray(0, 4); let header = ''; for (let i = 0; i < arr.length; i++) < header += arr[i].toString(16); >console.log(header); let type: any; switch (header) < case '89504e47': type = 'image/png'; break; case '47494638': type = 'image/gif'; break; case 'ffd8ffe0': case 'ffd8ffe1': case 'ffd8ffe2': case 'ffd8ffe3': case 'ffd8ffe8': type = 'image/jpeg'; break; default: type = 'unknown'; break; >console.log(type); >; 

Could you provide a comprehensive guide on how to utilize JavaScript to check file MIME type prior to uploading?

How to Validate File upload only image?, 2 Answers 2 You can do it in php with the mime type of the file. It’s a good idea to add the accept attribute. This will help the user

How to detect image file extension in a string with JavaScript [duplicate]

var str = "https://example.com/image.jpg"; var dotIndex = str.lastIndexOf('.'); var ext = str.substring(dotIndex); 

Fiddle

One might utilize a regular expression similar to the one below to detect image types, while ensuring that unwanted clutter is not included in the output. For instance,

'https://exmaple.com/image.jpg'.match(/[^/]+(jpg|png|gif)$/) -> ["image.jpg", "jpg"] 

var str = "https://example.com/image.jpg"; var extArray = str.split("."); var ext = extArray[extArray.length - 1]; 

Is there a way to easily check if the image url is valid or not?, Well, as I said this is more a general approach. If you want to be sure that it’s actually an image, you can utilize the Image object’s onerror

How to check type of uploaded image through FileReader?

It’s unnecessary to load the FileReader just to determine the file type. Referring to your code:

It’s a simple task to verify the file.type attribute.

It is possible to verify whether the given file is an image.

And which type of image is:

Please keep in mind that file.type.split(«/»)[1] must be in the form of an «image».

To verify the file extension, a comparable approach can be employed.

var extension = file.name.substring(file.name.lastIndexOf('.')); // Only process image files. var validFileType = ".jpg , .png , .bmp"; if (validFileType.toLowerCase().indexOf(extension)

Experiment with the extension selector by adopting this approach.

if($('img[src $= "jpg"]')) // if extension is jpg then dosomething dosomething; 

Validate image type using javascript, You can bind the onsubmit event of your form, and check if the value of your file input ends with «.jpg» or «.jpeg», something like this:

How to check if certain image format is uploaded

Change your if condition to:

if(!(fileExtension.indexOf($(this).val().split('.').pop().toLowerCase()) > -1)) 

if(!($.inArray($(this).val().split('.').pop().toLowerCase(),fileExtension) >-1)) 

var fileExtension = ['jpeg', 'tiff']; function MyFunc(e) < if(!(fileExtension.indexOf(e.split('.').pop().toLowerCase()) >-1))< alert('Format Not Accepted'); >else < alert("This Format Is Okay!"); >>

Image.tiff Image.gif Image.jpeg

var fileExtension = ['jpeg', 'tiff']; function MyFunc(e)< if(!($.inArray(e.split('.').pop().toLowerCase(),fileExtension) >-1)) < alert("Only formats allowed are: " + fileExtension.join(', ')); >>

 Image.tiff Image.gif Image.jpeg

If you require further clarification regarding the aforementioned source code, kindly leave a comment in the section provided below.

I hope this helps. Happy coding!

Check if image is uploaded from camera or gallery in mobile browser, There is an «original date» property in EXIF info which won’t be very easily changeable on phones. You can access EXIF tags easily by JavaScript

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Check Image Width, Height and its Type before Uploading using JavaScript

If, a web application (that you are working on) requires uploading of images (or files), then it is important to do some validations on the files before uploading. Here in this post, I’ll show how quickly and efficiently you can check the width, height and format of multiple images using plain JavaScript.

👉 &nbsp&nbspYou can also do this using jQuery. However, knowing how to do this using plain JavaScript is always good.

Along with the image width, height and its format, I’ll show you how to check the file’s last modified date.

In my markup section, I have an input box of type file . I want to check multiple files at a time, therefore I have added the multiple attribute to the input type.

I’ll check the details of the file(s) as soon as I select it. Therefore, I am using the onchange event to call a function to check the file details.

<html> <body> <input type="file" multiple onchange="checkFileDetails()" accept="image/*" /> <p ></p> <!--show the details--> </body>

<script> function checkFileDetails() < var fi = document.getElementById('file'); if (fi.files.length > 0) < // FIRST CHECK IF ANY FILE IS SELECTED. for (var i = 0; i files.length - 1; i++) < var fileName, fileExtension, fileSize, fileType, dateModified; // FILE NAME AND EXTENSION. fileName = fi.files.item(i).name; fileExtension = fileName.replace(/^.*\./, ''); // get image info using fileReader() readImageFile(fi.files.item(i)); > // GET THE IMAGE WIDTH AND HEIGHT USING fileReader() API. function readImageFile(file) < var reader = new FileReader(); // Create a new instance. reader.onload = function (e) < var img = new Image(); img.src = e.target.result; img.onload = function () < var w = this.width; var h = this.height; document.getElementById('fileInfo').innerHTML = document.getElementById('fileInfo').innerHTML + '<br /> ' + 'Name: <b>' + file.name + '</b> <br />' + 'File Extension: <b>' + fileExtension + '</b> <br />' + 'Size: <b>' + Math.round((file.size / 1024)) + '</b> KB <br />' + 'Width: <b>' + w + '</b> <br />' + 'Height: <b>' + h + '</b> <br />' + 'Type: <b>' + file.type + '</b> <br />' + 'Last Modified: <b>' + file.lastModifiedDate + '</b> <br />'; > >; reader.readAsDataURL(file); > > > </script> </html>

First, I’ll create a file object and loop through each files in the object. To get the file extension, I am using the replace() method with Regular Expressions.

The HTML DOM item() method provides some properties, using which you can get other details of the file(s). For example, add the below code inside the for loop.

The size property returns the file size in bytes. I am converting it into KB or Kilo Bytes by dividing it with 1024 . Since 1 Kilo Byte equals 1024 bytes.

However, if its an image file, we’ll have to use the fileReader API to get the width and height of image.

And, if you want you can do this using a super-duper method using jQuery. Check this out.

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Check image type in javascript

Last updated: Jan 9, 2023
Reading time · 3 min

# Check if a URL is an Image in JavaScript

To check if a URL is an image, call the test() method on a regular expression that matches an image extension at the end of a string, e.g. .png or .jpg .

The test() method will check if the URL ends with an image extension and will return true if it does.

Copied! 
function isImage(url)  return /\.(jpg|jpeg|png|webp|avif|gif|svg)$/.test(url); > // 👇️ true console.log(isImage('https://bobbyhadz.com/photo.jpg')); // 👇️ true console.log(isImage('https://bobbyhadz.com/photo.webp')); // 👇️ false console.log(isImage('https://bobbyhadz.com/index.html')); 

The RegExp.test method returns true if the regular expression is matched in the string and false otherwise.

We escaped the dot with a backslash. This is necessary because the dot has a special meaning in regular expressions.

The parentheses are called a capturing group and the pipe | symbol means «or», e.g. jpg or jpeg or png .

Either of the image extensions that are separated by pipe characters is a valid match, as long as they come after a dot and at the end of the string.

The dollar sign $ matches the end of the input. In other words, the string has to end with a .jpg extension.

This handles the edge case where the URL might contain an image extension anywhere else.

Copied! 
function isImage(url)  return /\.(jpg|jpeg|png|webp|avif|gif|svg)$/.test(url); > // 👇️ false console.log(isImage('https://example.jpeg.com')); 

You might have to add more image extensions to the regular expression if your server hosts images with other extensions.

# Making the regex more robust

You can check if the string starts with https:// or http:// if you want to make the regular expression stricter.

Copied! 
function isImage(url)  return /^https?:\/\/.+\.(jpg|jpeg|png|webp|avif|gif|svg)$/.test(url); > // 👇️ true console.log(isImage('https://bobbyhadz.com/photo.jpg')); // 👇️ true console.log(isImage('https://bobbyhadz.com/photo.webp')); // 👇️ false console.log(isImage('https://bobbyhadz.com/index.html')); 

The caret ^ matches the beginning of the input.

The string has to start with http or https .

The question mark ? matches the preceding item (the s character) zero or 1 times. This makes the s character optional.

We used backslashes to escape the forward slashes that follow the https:// protocol.

The last thing we added is a dot and a plus.

The dot . matches any single character and the plus + matches the preceding item one or more times.

This enables us to match any domain name.

In its entirety, the regular expression matches strings that start with https?:// and end with a dot and an image extension.

If you ever need help reading a regular expression, check out this regular expression cheatsheet by MDN.

It contains a table with the name and the meaning of each special character with examples.

# Additional Resources

You can learn more about the related topics by checking out the following tutorials:

I wrote a book in which I share everything I know about how to become a better, more efficient programmer.

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