Hooks, Theme, and Refs

Stable Version 1.0.0

This single function module is used in React components for deep merging specific property keys. This creates a simple, choesive pattern for passing props from "application code" to "shared library code".

Quick Start

First install in your project:

npm install hooks-theme-refs

Example of traditional usage:

import React, { Component } from 'react';
import htr from 'htr';

class SimpleComponent extends Component {
  render() {
    const { hooks, theme, status, label, ...rest } = htr(this);

    return (
      <div className={theme.simple} onClick={hooks.onClick} {...rest}>
        <i className={theme.icons[status]} />
        <span className={theme.label}>{label}</span>
      </div>
    );
  }

  static defaultProps = {
    hooks: {
      onClick() {},
    },

    theme: {
      simple: 'simple-component',
      label: 'simple-component-label,

      icons: {
        default: 'simple-component-icons-default',
        info: 'simple-component-icons-info',
      },
    },
  }
}

When to use refs

You will notice that refs are omitted from this component. As a rule refs are only added for required use cases. For instance, a video component should expose a way to get access to the video element. Wrapping HTML Form elements should expose a way to get access to the internals. Use good judgement, don't add a refs section for the sake of it.

Spread

A good rule of thumb with React components is to assume your consumer knows what they are passing to the component and forward that prop into the component. This allows any DOM event or property to be set easily.

Deep merging other props

By default htr focuses on hooks, theme, and refs. These are common to all well structured components. But your component may want to deep merge other keys, such as options. You can do this at a local or global level. For applications it may preferable to set once. For one off cases per Component, use the local approach.

Local

To locally merge a specific key, pass a list of keys as the second argument to the htr function.

const { options } = htr(this, ['options']);

To globally set keys:

htr.props.add('options');

// Anytime `htr` is called it will automatically deep merge `options`.
const { options } = htr(this);

API

htr(instance, extra, constructor)

• Required A React component instance
• Optional An array of extra property names to deep merge
• Optional The constructor (or plain object) to reference defaultProps from

htr.props

A global Set of whitelisted property keys. For instance you can whitelist options to be deep merged: htr.props.add('options').

Props

Props are organized into whitelisted keys that are specific to React components to reduce the amount of top level props. Each prop represents a part of well structured component.

Hooks

Are callback functions that are used by the component. They can be DOM events, but are not limited to that. You can pass to other libraries, use in your own logic, receive web socket events, etc.

If your component makes sense without the event, then do not set a default. This will allow the end user to disable any internal bound events, by passing a falsy value.

Theme

This is used to allow customization of classes or styles for internals. This helps prevent app developers from having to use CSS specificity to override styles, as they can provide their own classNames or styles directly on to sections of the component. They are compatible with CSS Modules and most theming providers.

Refs

This is useful when a parent may need an actual reference callback to the DOM node, for example a <video /> element so that it can perform additional operations or manipulation if necessary.

How this helps

Frequently, 3rd party components need to have input & customization tweaks from applications using them. These are often defined in the props that any component might accept, for example:

<Button onClick={appCallback} iconClass="search" />

This can get a bit trickier when components have a lot of internal sub-elements in their render methods. Imagine a render() method something like this:

class DefaultComponent extends Component {
  render() {
    const { icon, wrapper, showFilter, listItems, listItem } = this.props;
    const { onFilterClick, handleListClick } = this.props;
    const { listRefFn } = this.props;

    return (
      <div className={wrapperClass}>
        <i className={iconClass}/>

        <button className={showFilterClass} onClick={onFilterClick}>
          Filter List
        </button>

        <div className={listItemsClass} onClick={handleListClick} ref={listRefFn}>
          <span className={listItemClass}>Item 1</span>
          <span className={listItemClass}>Item 2</span>
          <span className={listItemClass}>Item 3</span>
        </div>
      </div>
    );
  }

  static defaultProps = {
    wrapperClass: 'default-wrapper',
    iconClass: 'default-icon',
    listItemsClass: 'list-items-wrapper',
    listItemClass: 'list-item',
    showFilterClass: 'show-filter-button',
    onFilterClick() {},
    handleListClick() {},
    listRefFn() {},
  }
}

While contrived, you can see that in order to allow users to not have to override classes and customize click behavior, the surface area of the props has started to increase. As the complexity or number of areas to control increase, hooks-themes-refs aims to help organize and clean these props up for both library authors and library consumers. Here's what the above example would look like after refactoring it to this pattern:

class DefaultComponent extends Component {
  render() {
    const { hooks, theme, refs, ...rest } = htr(this);

    return (
      <div className={theme.wrapper} {...rest}>
        <i className={theme.icon} />

        <button className={theme.showFilter} onClick={hooks.onFilterClick}>
          Filter List
        </button>

        <div className={theme.listItems} onClick={hooks.handleListClick} ref={refs.list}>
          <span className={theme.listItem}>Item 1</span>
          <span className={theme.listItem}>Item 2</span>
          <span className={theme.listItem}>Item 3</span>
        </div>
      </div>
    );
  }

  static defaultProps = {
    hooks: {
      onFilterClick() {},
      handleListClick() {},
    },

    theme: {
      wrapper: 'default-wrapper',
      icon: 'default-icon',
      listItems: 'list-items-wrapper',
      listItem: 'list-item',
      showFilter: 'show-filter-button',
    },

    refs: {
      list() {},
    },
  }
}

License

MIT 2018