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Ivan V.
Ivan V.

Posted on

Simplify your browser fetch() calls

This one is going to be short and sweet :). We are going to simplify using browser fetch function by creating a wrapper function (330 bytes gzipped) around fetch.

So after writing the fetch code probably hundreds of times, I've decided it's time to simplify it a little bit.

So instead of this:

try {
  const response = await fetch('https://example.com')
  // ok is true only for 200-299 response codes 
  if (response.ok) { 
    const data = await response.json()
  } else {
    throw response
  }
} catch (e) {
  console.log(e)
}
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I can do this:

import fetch from 'nice-fetch'

try {
  const [data, response] = await fetch('https://example.com')
} catch (e) {
  console.log(e)
}
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A small improvement I know, but it adds up over time :)

Usage

nice-fetch accepts the same arguments as regular fetch with one additional argument which is the type of the body from the response that you expect to be returned, the default value is json. This determines how the response body content should be handled.

// if (response.ok)
const data = await response.json() // <- json is the default
// } else {
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Other parameters are all available methods on the Body mixin

for example:

import fetch from 'nice-fetch'

// data is JSON (default)
const [data, response] = await fetch('https://example.com')

// data is JSON
const [data, response] = await fetch(
  'https://example.com',
  { method: 'GET' },
  'json' // <- explicit
)

// data is Blob
const [data, response] = await fetch(
  'https://example.com',
  { method: 'GET' },
  'blob'
)

// data is string
const [data, response] = await fetch(
  'https://example.com',
  undefined // <-- pass undefined for RequestInit
  'text'
)
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Return values

The function returns a tuple of data, which is already handled response content (no need for response.json() call) and the original response object.

Error handling

When you write code like this, all errors can be handled in the catch block.

try {
  const [data, response] = await fetch('https://example.com')
} catch (e) {
  console.log(e)
}
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In case that the response.ok is not true (status is not in the range 200–299) fetch will throw with the full Response object

In case that the response body content can't be properly handled e.g. invalid JSON, the function will rethrow the error.

In case there is an error from the fetch call itself ( Network request failed, timeout) function will also rethrow that error.

You can install it with:

npm i nice-fetch
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repository: nice-fetch
I hope you find it useful.

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