Response

`Response.prototype.blob`

Takes a Response stream and reads it to completion, returning the result as a Blob

Syntax

JavaScript

response.blob()

Return Value

A Promise that resolves to a Blob

Examples

Basic Usage

const response = await fetch('/image.png')
const blob = await response.blob()
const url = URL.createObjectURL(blob)
console.log(url)

Practical Example

async function downloadFile(url: string, filename: string) {
  const res = await fetch(url)
  const blob = await res.blob()
  const a = document.createElement('a')
  a.href = URL.createObjectURL(blob)
  a.download = filename
  a.click()
}

Advanced Usage

const res = await fetch('/api/export')
const blob = await res.blob()
console.log('Size:', blob.size, 'Type:', blob.type)

Understanding Response.prototype.blob

The Response.prototype.blob method in JavaScript takes a Response stream and reads it to completion, returning the result as a Blob. It belongs to the Response object and is one of the most widely used methods for working with response values in modern JavaScript and TypeScript applications.

The method signature is response.blob(). When called, it returns a promise that resolves to a blob. Understanding when and how to use blob() helps you write more expressive, readable code.

Common use cases for Response.prototype.blob include data transformation, input validation, API response processing, and building reusable utility functions. It works well alongside related methods like fetch-response-text, fetch-response-json, fetch-response-arraybuffer, enabling you to chain operations together for complex data manipulation pipelines.

Browser support for Response.prototype.blob is excellent across all modern browsers including Chrome, Firefox, Safari, and Edge. It is also fully supported in Node.js and Deno. For older environments, transpilation with Babel or a polyfill may be needed.