005-interop-with-react.md

Interop with React

In the prior chapter, we learned how to update an existing audio graph whenever a HTMLInputElement fires a change event. Can we handle the visual UI with React while supporting JSX-declared audio graphs with Wax?

The problem is that we need to be able to use React.createElement and createAudioElement at the same time. What if we could compose a single pragma that can select whether to use the former or the latter at runtime? The withReact example app has a solution:

/** @jsx createElement */

import {
    isWaxComponent,
    ...
} from 'wax-core';

import combineElementCreators from './combineElementCreators';

const createElement = combineElementCreators(
    [isWaxComponent, createAudioElement],
    [() => true, React.createElement],
);

combineElementCreators is a function that takes a mapping between predicates and pragmas, and returns a new pragma to be targeted by our transpiler. In our example, if an element belongs to Wax (determined using the exposed isWaxComponent binding), then the createAudioElement pragma will be invoked; otherwise, we'll default to React.createElement. combineElementCreators isn't provided by Wax but can be implemented with a few lines of code:

const getCreator = (map, Component) =>
    [...map.entries()]
        .find(([predicate]) => predicate(Component))[1];

const combineElementCreators = (...creatorBindings) => {
    const map = new Map(creatorBindings);

    return (Component, props, ...children) => {
        const creator = getCreator(map, Component);
        return creator(Component, props, ...children);
    };
};

We can then instruct Babel to target this pragma in the usual way:

{
    "presets": [
        ["@babel/react", {
            "pragma": "createElement"
        }]
    ]
}

The aforementioned withReact example demonstrates how ReactDOM.render and renderPersistentAudioGraph can be used across a single app.