blob-utils

Lightweight TypeScript utilities for Blob, File, Base64, object URLs, and browser downloads.

Version: 1.0.2

License: MIT

Developer: Sanish Vasudevan

Installation

npm install blob-utils

Exported Utilities

• base64ToBlob(base64, mimeType?)
• isBase64(str)
• getMimeType(base64)
• blobToFile(blob, filename)
• base64ToFile(base64, filename)
• toObjectURL(blob)
• revokeObjectURL(url)
• createObjectURL(blob)
• releaseObjectURL(url)
• downloadBlob(blob, filename)
• downloadBase64(base64, filename)
• downloadFromUrl(url, filename?)

Quick Usage

import {
  base64ToBlob,
  base64ToFile,
  blobToFile,
  toObjectURL,
  revokeObjectURL,
  createObjectURL,
  releaseObjectURL,
  downloadBlob,
  downloadBase64,
  downloadFromUrl,
  getMimeType,
  isBase64,
} from 'blob-utils'

const dataUrl = 'data:text/plain;base64,SGVsbG8sIHdvcmxkIQ=='

const blob = base64ToBlob(dataUrl)
const file = base64ToFile(dataUrl, 'hello.txt')
const sameAsFile = blobToFile(blob, 'copy.txt')

console.log(isBase64(dataUrl)) // true
console.log(getMimeType(dataUrl)) // text/plain

const objectURL = createObjectURL(blob)
releaseObjectURL(objectURL)

const legacyURL = toObjectURL(blob)
revokeObjectURL(legacyURL)

downloadBlob(blob, 'hello.txt')
downloadBase64(dataUrl, 'hello-base64.txt')
await downloadFromUrl('https://example.com/report.pdf', 'report.pdf')

API Tutorials

base64ToBlob(base64, mimeType?)

Converts raw base64 or a data URL into a Blob.

import { base64ToBlob } from 'blob-utils'

const dataUrl = 'data:text/plain;base64,SGVsbG8='
const blob = base64ToBlob(dataUrl)
const pngBlob = base64ToBlob('iVBORw0KGgoAAAANSUhEUgAA...', 'image/png')

isBase64(str)

Checks whether a string is valid raw base64 or valid data URL payload.

import { isBase64 } from 'blob-utils'

isBase64('SGVsbG8=') // true
isBase64('data:text/plain;base64,SGVsbG8=') // true
isBase64('not-base64') // false

getMimeType(base64)

Extracts MIME type from a data URL. Returns null for plain base64.

import { getMimeType } from 'blob-utils'

getMimeType('data:image/png;base64,iVBORw0KGgo...') // image/png
getMimeType('SGVsbG8=') // null

blobToFile(blob, filename)

Converts a Blob to a browser File.

import { blobToFile } from 'blob-utils'

const blob = new Blob(['hello'], { type: 'text/plain' })
const file = blobToFile(blob, 'hello.txt')

base64ToFile(base64, filename)

Converts raw base64 or data URL directly to File.

import { base64ToFile } from 'blob-utils'

const file = base64ToFile('data:text/plain;base64,SGVsbG8=', 'hello.txt')

createObjectURL(blob) and releaseObjectURL(url)

Preferred object URL helpers.

import { createObjectURL, releaseObjectURL } from 'blob-utils'

const blob = new Blob(['preview'])
const url = createObjectURL(blob)

// use URL in img/video/a tags...

releaseObjectURL(url)

toObjectURL(blob) and revokeObjectURL(url)

Equivalent helpers with alternate naming.

import { toObjectURL, revokeObjectURL } from 'blob-utils'

const blob = new Blob(['preview'])
const url = toObjectURL(blob)
revokeObjectURL(url)

downloadBlob(blob, filename)

Triggers browser download for a Blob.

import { downloadBlob } from 'blob-utils'

const blob = new Blob(['hello'], { type: 'text/plain' })
downloadBlob(blob, 'hello.txt')

downloadBase64(base64, filename)

Triggers browser download from raw base64 or data URL.

import { downloadBase64 } from 'blob-utils'

downloadBase64('data:text/plain;base64,SGVsbG8=', 'hello.txt')

downloadFromUrl(url, filename?)

Fetches a file URL and downloads it in the browser.

import { downloadFromUrl } from 'blob-utils'

await downloadFromUrl('https://example.com/manual.pdf', 'manual.pdf')

// If filename is omitted, the name is inferred from URL path.
await downloadFromUrl('https://example.com/files/report.csv')

Notes

• This package is browser-focused (Blob, File, URL, document, fetch APIs).
• For downloadFromUrl, cross-origin servers must allow fetch access (CORS).