The blob-util npm package is a collection of utilities for working with Blob objects in JavaScript. It simplifies common tasks such as converting blobs to base64 strings, creating blobs from various data types, and more. This package is particularly useful when dealing with binary data in web applications, making it easier to handle file uploads, image processing, and other blob-related operations.
Convert Blob to Base64 String
This feature allows you to convert a Blob object into a base64 encoded string. This is useful for uploading files as base64 encoded strings or displaying images directly in the browser using the base64 string.
blobUtil.blobToBase64String(blob).then(function (base64String) {
// use your base64 string here
}).catch(function (err) {
// handle any errors
});Create Blob from Base64 String
This feature enables the creation of a Blob object from a base64 encoded string. It's useful for retrieving images or files that are stored as base64 strings and converting them back into a usable Blob format.
blobUtil.base64StringToBlob(base64String).then(function (blob) {
// use your blob here
}).catch(function (err) {
// handle any errors
});Convert Blob to Binary String
This functionality converts a Blob into a binary string. This can be useful for processing or analyzing the binary data of files directly in JavaScript.
blobUtil.blobToBinaryString(blob).then(function (binaryString) {
// use your binary string here
}).catch(function (err) {
// handle any errors
});FilePond is a flexible and fun JavaScript file upload library that can handle multiple files and has extensive options for image preview, file validation, and drag and drop. It's more focused on the UI aspect of file handling compared to blob-util, but it also deals with Blob objects when processing files.
Pica is a library designed for resizing images in the browser with high quality and performance. While it primarily focuses on image processing, it works with Blob objects for loading and saving images. Compared to blob-util, Pica is more specialized in image manipulation.
blob-util is a Blob library for busy people.
If you want an easy way to work with binary data in the browser, or you don't even know what a Blob is, then this is the library for you.
blob-util offers a tiny (~4KB min+gz) set of cross-browser utilities for translating Blobs to and from different formats:
<img/> tagsIt's also a good pairing with the attachment API in PouchDB.
Note: this is a browser library. For Node.js, see Buffers.
Topics:
Download it from the dist/ folder above, or use NPM:
$ npm install blob-util
or Bower:
$ bower install blob-util
Then stick it in your HTML:
<script src="blob-util.js"></script>
Now you have a window.blobUtil object. Or if you don't like globals, you can use Browserify.
Blobs (binary large objects) are the modern way of working with binary data in the browser. The browser support is very good.
Once you have a Blob, you can make it available offline by storing it in IndexedDB, PouchDB, LocalForage, or other in-browser databases. So it's the perfect format for working with offline images, sound, and video.
Here's Kirby. He's a famous little Blob.
So let's fulfill his destiny, and convert him to a real Blob object.
var img = document.getElementById('kirby');
blobUtil.imgSrcToBlob(img.src).then(function (blob) {
// ladies and gents, we have a blob
}).catch(function (err) {
// image failed to load
});
(Don't worry, this won't download the image twice, because browsers are smart.)
Now that we have a Blob, we can convert it to a URL and use that as the source for another <img/> tag:
var blobURL = blobUtil.createObjectURL(blob);
var newImg = document.createElement('img');
newImg.src = blobURL;
document.body.appendChild(newImg);
So now we have two Kirbys - one with a normal URL, and the other with a blob URL. You can try this out yourself in the blob-util playground. Super fun!
Warning: this API uses Promises, because it's not 2009 anymore.
###Overview
###createBlob(parts, options)
Shim for
new Blob()
to support
older browsers that use the deprecated BlobBuilder API.
Params
Array - content of the BlobObject - usually just {type: myContentType}Returns: Blob
###createObjectURL(blob)
Shim for
URL.createObjectURL()
to support browsers that only have the prefixed
webkitURL (e.g. Android <4.4).
Params
BlobReturns: string - url
###revokeObjectURL(url)
Shim for
URL.revokeObjectURL()
to support browsers that only have the prefixed
webkitURL (e.g. Android <4.4).
Params
string
###blobToBinaryString(blob)
Convert a Blob to a binary string. Returns a Promise.
Params
BlobReturns: Promise - Promise that resolves with the binary string
###base64StringToBlob(base64, type)
Convert a base64-encoded string to a Blob. Returns a Promise.
Params
stringstring | undefined - the content type (optional)Returns: Promise - Promise that resolves with the Blob
###binaryStringToBlob(binary, type)
Convert a binary string to a Blob. Returns a Promise.
Params
stringstring | undefined - the content type (optional)Returns: Promise - Promise that resolves with the Blob
###blobToBase64String(blob)
Convert a Blob to a binary string. Returns a Promise.
Params
BlobReturns: Promise - Promise that resolves with the binary string
###dataURLToBlob(dataURL)
Convert a data URL string
(e.g. 'data:image/png;base64,iVBORw0KG...')
to a Blob. Returns a Promise.
Params
stringReturns: Promise - Promise that resolves with the Blob
###imgSrcToDataURL(src, type, crossOrigin)
Convert an image's src URL to a data URL by loading the image and painting
it to a canvas. Returns a Promise.
Note: this will coerce the image to the desired content type, and it will only paint the first frame of an animated GIF.
Params
stringstring | undefined - the content type (optional, defaults to 'image/png')string | undefined - for CORS-enabled images, set this to
'Anonymous' to avoid "tainted canvas" errorsReturns: Promise - Promise that resolves with the data URL string
###canvasToBlob(canvas, type)
Convert a canvas to a Blob. Returns a Promise.
Params
stringstring | undefined - the content type (optional, defaults to 'image/png')Returns: Promise - Promise that resolves with the Blob
###imgSrcToBlob(src, type, crossOrigin)
Convert an image's src URL to a Blob by loading the image and painting
it to a canvas. Returns a Promise.
Note: this will coerce the image to the desired content type, and it will only paint the first frame of an animated GIF.
Params
stringstring | undefined - the content type (optional, defaults to 'image/png')string | undefined - for CORS-enabled images, set this to
'Anonymous' to avoid "tainted canvas" errorsReturns: Promise - Promise that resolves with the Blob
###arrayBufferToBlob(buffer, type)
Convert an ArrayBuffer to a Blob. Returns a Promise.
Params
ArrayBufferstring | undefined - the content type (optional)Returns: Promise - Promise that resolves with the Blob
###blobToArrayBuffer(blob)
Convert a Blob to an ArrayBuffer. Returns a Promise.
Params
BlobReturns: Promise - Promise that resolves with the ArrayBuffer
Thanks to webmodules/blob for the Blob constructor shim, and to the rest of the PouchDB team for figuring most of this crazy stuff out.
npm install
npm run build
To generate documentation in doc/:
npm run jsdoc
or in markdown format as api.md
npm run jsdoc2md
The playground is just jsdoc with some extra text containing Kirby and the code samples and such.
So unfortunately you will need to do a manual diff to get the docs up to date. You'll need to diff:
api.md to README.mdindex.html to doc/global.htmlRun npm run dev and then point your favorite browser to http://127.0.0.1:8001/test/index.html.
The query param ?grep=mysearch will search for tests matching mysearch.
You can run e.g.
CLIENT=selenium:firefox npm test
CLIENT=selenium:phantomjs npm test
This will run the tests automatically and the process will exit with a 0 or a 1 when it's done. Firefox uses IndexedDB, and PhantomJS uses WebSQL.
FAQs
Utilities for working with Blob objects in the browser
The npm package blob-util receives a total of 2,024,457 weekly downloads. As such, blob-util popularity was classified as popular.
We found that blob-util demonstrated a not healthy version release cadence and project activity because the last version was released a year ago. It has 1 open source maintainer collaborating on the project.
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