In this lesson, we’ll look at the propPath utility function. We’ll ask for a property multiple levels deep in an object and get back a Maybe. We’ll get a Just when the property exists at our path and a Nothing if any part of the path is undefined.
const propPath = require(‘crocks/Maybe/propPath‘) const user = { username: ‘tester‘, email: ‘test@gmail.com‘, address: { street: ‘111 E. West St‘, city: ‘Anywhere‘, state: ‘PA‘, postalCode: ‘19123-4567‘ } }; const getPostalCode = propPath([‘address‘, ‘postalCode‘]); const zip = getPostalCode(user).option(‘not available‘); console.log(zip) //‘19123-4567‘
[Javascript Crocks] Safely Access Nested Object Properties with `propPath`
原文：https://www.cnblogs.com/Answer1215/p/9026452.html