Comparing corresponding elements of two equal-length arrays
I don't know TypeScript or lodash, but I hope the following code is at least almost correct. You should be able to use zip and map to solve the problem in a functional manner.

function changed(a, b) {
    return _.zip(a, b).map(x =&gt; { return x[0] !== x[1] });
}


Basically, the problem of what has changed can be rephrased as which elements are equal.