Mastering JavaScript Functional Programming - Second Edition

Getting a property

Back in the Getting a property from an object section of Chapter 6, Producing Functions – Higher-Order Functions, we wrote a simple getField() function that could handle getting a single attribute out of an object. (See question 6.5 in that chapter for the missing companion setField() function.) Let's take a look at how we can code this. We can have a straightforward version, as follows:

const getField = attr => obj => obj[attr];

We can even go one better by applying currying so that we have a more general version:

const getField = curry((attr, obj) => obj[attr]);

We could get a deep attribute out of an object by composing a series of applications of getField() calls, but that would be rather cumbersome. Instead, let's ...