protectFromUnmount

protectFromUnmount.js

function protectFromUnmount() {

    let callbacks = {};
    let count = 0;
    const noop = value => value;

    const wrapCallback = id => function(...params) {
        const raceSafeCallbacks = callbacks;

        if (!raceSafeCallbacks)
            return noop(...params);

        const callback = raceSafeCallbacks[id];
        delete raceSafeCallbacks[id];
        return callback(...params);
    };

    const protect = (callback) => {
        const raceSafeCallbacks = callbacks;

        if (!raceSafeCallbacks)
            return noop;

        const id = count++;
        raceSafeCallbacks[id] = callback;
        return wrapCallback(id);
    };

    protect.unmount = () => callbacks = null;
    return protect;
}

This is great. Tagging this with the GitHub issue that brought me here.