addhoc

Handy little helper to create proper HOC functions complete with hoisted statics and forwarded refs

Motivation

As defined in the React documentation, a Higher Order Component, or HOC, is a function that returns a React component that wraps a specified child component and often provides augmented functionality. Implementing HOCs can be hard, especially when considering hoisting statics, managing ref forwarding, and handling display name. addhoc aims to handle these challenges for you.

Benefits

addhoc creates HOC functions that automatically:

• pass through unrelated props
• wrap the display name for easy debugging
• hoist non-React statics
• forward refs

Installation

npm install addhoc

API

/**** Public API ****/
// This is the main exported entrypoint
addhoc(renderFn: Function, [name: String = 'WithHOC'], [...extraArgs]): Function

/**** Signatures, not exported API ****/
// This is the signature of the renderFn parameter to addhoc()
renderFn(getWrappedComponent: Function, [...extraArgs]): React.Component

// This is the signature of the getWrappedComponent parameter to renderFn()
getWrappedComponent([additionalProps: Object]): React.Component

Usage

addhoc is a function that returns a HOC function. To construct your HOC, you simply pass a callback that acts as the render function of your top-level component. Your callback is provided a function parameter that returns the wrapped child that's initially provided to the HOC. You can call that callback with an object of props to add to the wrapped component.

Example 1: Adding a prop

import addhoc from 'addhoc';
import MyComponent from './my-component';

const withFooProp = addhoc(getWrappedComponent => getWrappedComponent({ foo: true }), 'WithFooProp');
const MyComponentWithFoo = withFooProp(MyComponent);
// Rendering a MyComponentWithFoo will create a MyComponent with prop foo = true

Example 2: Wrapping in another component

import React from 'react';
import addhoc from 'addhoc';
import MyComponent from './my-component';

const withDiv = addhoc(getWrappedComponent =>
  <div>
    { getWrappedComponent() }
  </div>, 'WithDiv');
const MyComponentWithDiv = withDiv(MyComponent);
// Rendering a MyComponentWithDiv will render a div that wraps a MyComponent

Example 3: React 16 Context consumer

import React from 'react';
import addhoc from 'addhoc';
import MyComponent from './my-component';

const MyContext = React.createContext('DefaultValue');
const withMyContext = addhoc(getWrappedComponent =>
  <MyContext.Consumer>
    { value => getWrappedComponent({ value }) }
  </MyContext.Consumer>, 'WithMyContext');
const MyComponentWithMyContext = withMyContext(MyComponent);

// ...
render() {
  return <MyContext.Provider value='ProvidedValue'>
    <MyComponentWithMyContext />
  </MyContext.Provider>
}

// Now, the MyComponentWithMyContext automatically gets a prop called `value` that gets the context value passed in from
// the context.

Example 4: Passing through configuration

Sometimes, you want to set some values as part of assembling the HOC and have those available in your render function. You can pass arbitrary parameters after the name param to addhoc and they'll be passed through as additional parameters to your render function:

import addhoc from 'addhoc';
import MyComponent from './my-component';

const withFooProp = addhoc((getWrappedComponent, extra) => getWrappedComponent({ foo: extra }), 'WithFoo', 'EXTRA');
const MyComponentWithFoo = withFooProp(MyComponent);
// Rendering a MyComponentWithFoo will get a `foo` prop with value `EXTRA`

Testing

npm test