Reduce build size by swapping out lodash.assign for a minimal Object.assign

[olov]

I did a clone of the repo followed by NODE_ENV=production scripts/build, which produced a 16826 bytes react-modal.min.js (5358 bytes gzipped).

Replacing the lodash assign import in ModalPortal.js with a minimal Object.assign polyfill (I took the TS one just for example):

function assign(t) {
    for (var s, i = 1, n = arguments.length; i < n; i++) {
        s = arguments[i];
        for (var p in s) if (Object.prototype.hasOwnProperty.call(s, p))
            t[p] = s[p];
    }
    return t;
}

...produced a 14516 bytes react-modal.min.js (4418 bytes gzipped).

That's an 18% (gzipped size) reduction, which adds up on slow networks and devices.

[jdalton]

In this case since only lodash.assign is being used you should totally replace it with babel-plugin-transform-object-assign. In other cases, when using Lodash and size is a concern, you should check out lodash-webpack-plugin. It disables features sets and edge cases by default to reduce bundle sizes.