Polyfill newer JS features. Primarily targeted at older phones (for example, iOS 8) that will still run React Native. This library mutates JavaScript's built-in objects and should be used judiciously.

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1.2.16 years ago6 years agoMinified + gzip package size for react-native-polyfill in KB




Some JS engines that are targeted by React Native, particularly iOS 8 and, to a lesser extent, Android 6, are missing some of the new ES2015 functions and they may not be polyfilled by a typical build system.
This leads to errors that look like this:
Unhandled JS Exception: undefined is not a function (evaluating ‘Number.parseInt’)

A lot of these functions are the ones that existed in prior versions of JavaScript but were added to the Number object to namespace them. For example:
parseInt('20', 10); // existing JavaScript function
Number.parseInt('20', 10); // the 'new' way of accessing the same function as of ES2015


npm install --save react-native-polyfill

To use the entire package and mutate the base objects, simply import or require the package:
import 'react-native-polyfill';

If you only want the Array or Number polyfills, you can include just one:
import 'react-native-polyfill/src/Array';

If you just want a single function or you want to limit the number of changes to the base object, you can access the functions directly:
const includes = require('react-native-polyfill/src/Array/includes');


Where available, this project has used the MDN polyfills or a close variation.


Importing this package into your project will mutate the prototype of JavaScript's base objects, if those objects do not already support the functionality. The decision to mutate these base objects in your code base should not be taken lightly. The polyfills in this package should be relatively low risk as they do not change prototypes in JavaScript engines that already implement the functions.

Polyfilled Functions


  • includes


  • isInteger
  • isNaN
  • isSafeInteger
  • parseFloat
  • parseInt


  • codePointAt
  • fromCodePoint
  • normalize // Uses the unorm library for a polyfill


More information about this topic can be found at: