Overview

Utility for shouldComponentUpdate in React and Preact. Deeply compares props and state to detect changes and avoid unnecessary renders.

Intended for plain data structures such as {} and []. Any other objects are compared by reference: ===, not by structure.

Tiny, dependency-free, single file, native module.

Why

shouldComponentUpdate is critical for the performance of frequently-updated views in React and Preact applications. React claims to implement shallow comparison in PureComponent, but what you really want is a deep comparison, which they don't provide.

As a rule of thumb, traversing data structures is much cheaper than making new ones. The cost of a deep shouldComponentUpdate is neglibible compared to the cost of rendering that it avoids.

Sticking this on all your classes is a no-brainer.

Installation

npm i -E react-change

Usage

import {Component} from 'react'
import {shouldComponentUpdate} from 'react-change'

class ViewComponent extends Component {
  shouldComponentUpdate() {
    return shouldComponentUpdate.apply(this, arguments)
  }
}

You can stick this in a base class for all your components.

Changelog

0.3.1

Support equality for Date and URL objects.

0.3.0

Now dependency-free and provided as a native module.

Misc

I'm receptive to suggestions. If this library almost satisfies you but needs changes, open an issue or chat me up. Contacts: https://mitranim.com/#contacts