Higher Order Component for Handling Promises in React

pend.js

function pend(getPromises, Child) {
	return class extends Component {
		constructor(props) {
			super(props);

			let promises = getPromises(props);

			this.state = { pending: promises };

			Object.entries(promises).forEach(([name, promise]) => {
				promise.then(
					result => {
						this.setState(state => {
							let nextState = { [name]: result };
							let pending = state.pending;

							delete pending[name];

							if (Object.keys(pending) === 0) {
								nextState.pending = false;
							} else {
								nextState.pending = pending;
							}

							return nextState;
						});
					},
					error => {
						this.setState(state => {
							let rejected = state.rejected || {};
							rejected[name] = error;

							return { rejected };
						});
					},
				);
			});
		}
		render() {
			let props = { ...this.props, ...this.state };
			return <Child {...props} />;
		}
	};
}