Promise chains can be a powerful way to handle a series of transformations to the results of an async call. In some cases, additional promises are required along the way. In cases where there are no new promises, function composition can reduce the n…

In this lesson we'll use a handful of Ramda's utility functions to take a queryString full of name/value pairs and covert it into a JavaScript object so we can access those properties in a more useful way. Along the way, we'll build up a composition…

Naming things is hard and arguments in generic utility functions are no exception. Making functions "tacit" or "point free" removes the need for the extra parameter names and can make your code cleaner and more succinct. In this lesson…

Learn how to write a promise based delay function and then use it in async await to see how much it simplifies code over setTimeout. Lets say you want to call a function after 1s, 2s, 3s. You can use setTimeout, or you can wrap it up into a simple de…

Function composition allows us to build up powerful functions from smaller, more focused functions. In this lesson we'll demystify how function composition works by building our own compose and composeAll functions. // __test__ import {add, inc, dbl,…

In this lesson, we'll use Promise.all to get an array that contains the resolved values from multiple promises. Then we'll see how we can use Ramda to convert that array of values into a single object using zip with fromPairs. Then we'll refactor to…

In this lesson we'll take some existing code and refactor it using some functions from the Ramda library, most notably, compose and converge. When we're done, we'll have taken a function with a couple of local variables and parameter references and c…

In functional programming, we create large functions by composing small functions; in object-oriented programming, we create large objects by composing small objects. They are different types of composition. They might sound similar, but there is som…

In this lesson, we'll use Ramda's toPairs function, along with map, join, concatand compose to create a reusable function that will convert an object to a querystring. const R = require('ramda'); const {map, join, concat, compose, toPairs} = R; const…

In this lesson, we'll filter a list of objects based on multiple conditions and we'll use Ramda's allPass function to create a joint predicate from multiple, individual predicate functions. const R = require('ramda'); const { allPass, propEq, lte, pr…