It also reads the same way as a promise chain. negate is our fifth most imported Lodash function. It's bit more complex than the others since an implementation would be interceptorFunction => input => { interceptorFunction(input); return input; }. Sure, it's handled well in vanilla Lodash, but give it unexpected arguments, expected unexpected results. Why Lodash? I love the function and one might wonder why we only have 10 imports. Again we don't have a specific rule about it, but Lodash's map applies to object and map collections, can use the builtin get style iterator and benefit from the curry/data-last FP combo. By convention, Lodash module is mapped to the underscore character. These are mostly simple functional wrappers that fit well the API of not only our tools but all the JS ecosystem and base language. GitHub Gist: instantly share code, notes, and snippets. Support To that purpose, we only have to call the. A modern JavaScript utility library delivering modularity, performance, & extras. This method is like _.find except that it returns the index of the first element that passes the callback check, instead of the element itself. It provides invaluable algorithmic tools that can save developers lines of code, time and bugs. Lodash is a Javascript library that provides utility methods for convenience, which are not by default provided with the vanilla javascript. Its curry feature also leads to building many unary functions (functions that take only one argument) that are fantastic for function composition. The team made an early decision in favor of flow.. Finally, there is a list of contenders that can seem very strange for an imperative programmer. lodash fp docs. Lodash is a great library, well crafted, battle tested and with a strong team. And then it takes the function that you wanna curry. After close examination, all the forEach are justified. Here is the whole list of our Lodash function imports in one of our Front-End codebase. The resulting patch() is a higher-order function that returns new function that transforms objects based on provided recipe. Difference Between Lodash _.assign and _.assignIn In Lodash, both _.assign and _.assignIn are ways to copy source objects’ properties into target object. Methods that retrieve a single value or may return a primitive value will automatically end the chain returning the unwrapped value. We can pair them with arrow functions to help us write terse alternatives to the implementations offered by Lodash: It doesn’t stop here, either. Complementary Tools. Native map x 9,512 ops/sec ±1.19% (90 runs sampled) Lodash map x 69,592 ops/sec ±0.90% (90 runs sampled) Lodash fp map x 293,734 ops/sec ±1.26% (87 runs sampled) This is a typical FP tool used for function composition (aka function centipede). I told you that it "abstracts away from you the chore (and complexity) of looping", so that you can focus on what really matters for your application: the collection you want to iterate through, and the piece of logic you wish to be applied for each item.. You use forEach like this: Since. map usage seems pretty standard to me. There are several ways to perform function composition, they are illustrated below with different implementations of the same function: compose is often the classic tool for people coming from an FP background as it reads in the same way as the manual composition, but flow reads sequentially left to right and is, therefore, the first choice of all other people. We use a functional programming style to favor meaning over absolute code performance (which is tackled by other means). Lodash helps programmers write more concise and easier to maintain JavaScript code. Hi! Most JS software developers have some experience with Lodash or Underscore and very few are familiar with the concepts behind Ramda or Pointfree-fantasy. We have no general rule about when to use a writing style that shows the reader how an operation is performed (map('propertyA')) or one that shows its meaning and abstracts the implementation (const formatForUI = capitalize). So, let’s late a look at the main differences. I recently performed a small analysis of our usage of the library to spot some weird usages that have slipped through code reviews and make a small retrospective about how this tool and functional programming are used in a mature production app. Docs Lodash Documentation for Lodash 4.17.11 Documentation for Lodash (version 4.17.1) A modern JavaScript utility library delivering modularity, performance & extras. This package is already installed when you have Lodash installed! But let's go back to our iterators. Importing lodash functions from lodash-es. I have countless times seen people use in code interview as a poor's man map or reduce. Test your JavaScript, CSS, HTML or CoffeeScript online with JSFiddle code editor. identity is used in a variety of situations like with a filter, groupBy or sortBy. “Fp” for functional programming. They work with unaries (see where we're going...) and enable to write very readable and pure functions: If you compare to chained APIs, this is incredibly superior. We often wrap side effects with tap even if they already return their input when we want to signal at that the original data is forwarded and/or that a side effect is taking place. Stack Overflow for Teams is a private, secure spot for you and your coworkers to find and share information. _.findIndex(array, [callback=identity], [thisArg]) source npm package. Let's dig in after a small digression about the lib itself. One often unquoted benefit is the reduction in bug density due to the avoidance of index manipulation. [00:02:52] And curryN takes as its first input, the number that you want to curry for, so in this case it's three. Just to be clear: you should probably use Lodash – just make sure you import the bits you need, not the whole library to use one method. Contributing; Release Notes; Wiki (Changelog, Roadmap, etc.) These are nice getters functions that allow to define a path for an attribute in a simple or complex object and retrieve the value. Teams. These two functions have two pros and one con: The getters can easily be extracted and shared. If a property name is provided for callback the created ".pluck" style callback will return the property value of the given element. Of course, it means a lot of unaries easy to name, reuse, test and compose. Lodash/fp. On the same occasion, we stopped spending time on the best way to detect null from undefined or checking is a number is really a number. Speaking of performance, we have what I would consider a high number of memoize imports in the codebase, especially after having most of the expensive stuff in redux selectors already using memoization techniques from the fantastic reselect library. That can be explained easily by the fact that we have very few complex branching in our codebase and the vast majority of them are using cond. Lodash contains tools to simplify programming with strings, numbers, arrays, functions and objects. Lodash is available in a variety of builds & module formats. Documentation makes it seem like fp.partial optionally accepts an array, but it they're mandatory. A programmer uses functional utilities in his lifetime as many times as he blinks. This is less precise than counting the number of usages of each function but this still gives a good representation of our usage. These collection methods make transforming data a breeze and with near universal support. Our global Lodash usage reflects a lot about how our team thinks and solves technical problems. // FP variant puts the data as last argument (and this is great). It uses a functional programming paradigm. */, /*--------------------------------------------------------------------------*/. This can look original for something that dumb. // The function only need the last argument to be executed. YOU MIGHT NOT NEED LODASH. // Here we put the currying into practice to build a getter function. Example The lodash/fp module promotes a more functional programming (FP) friendly style by exporting an instance of lodash with its methods wrapped to produce immutable auto-curried iteratee-first data-last methods. Classic point-free style bonus, it also reads very well and is hard to typo. About Lodash's forEach function, and Lodash in general…. lodash/fp doc generator. The number of if and ternaries is much much bigger. Redux's selector still relies on nice old switch statements. Lodash Library is very light weight (Just 4KB gzipped) and this is the top #1 library by downloads in NPM registry In the same spirit, the team favors functional tools to perform direct access to specific elements in an array (head, tail) or array destructuring. Table of Contents About 1 Chapter 1: Getting started with lodash 2 Remarks 2 Versions 2 Examples 5 Setup 5 node.js with npm 5 Download own copy for clientside in website (ie. - lodash/lodash In Lodash/fp, and this will be the same for the next slide we will look at. The team made an early decision in favor of flow. reduce might an FP star, but in the end, Lodash's utilities, probably often built on top of reduce solves most of our use cases. Wow, I didn't expect to have so few reduces and so many forEach. From the start, we've been using aggressively the Lodash FP library through our whole JS & TS codebase, whether it's on the Back-End or Front-End. The, Pro: The FP variant of these functions shines. Flow comes next in our list (80 imports). My current project is completing its third year. Lodash comes with handful of befitting… Lodash was inspired by Underscore.js. Creates a lodash object which wraps value to enable implicit chaining. These tools are the best friend of point-free functional programming adepts. _.chunk(array, [size=1]) source npm package. Although it's not mandatory to use pure functions, they provide a lot of benefits. The spirit is the same. We don't have a specific policy to access all attributes like that, but it makes a lot of sense when using the FP variant of Lodash and a point-free style. Lodash FP aims to combine the great functionality given by the library and the ideas of functional programming. Lodash’s modular methods are great for: Iterating arrays, objects, & strings; [size=1] (number): The length of each chunk Returns (Array): Returns the new array of chunks. The example above also features stubTrue and identity. // This is why we like data-last functions. compose is often the classic tool for people coming from an FP background as it reads in the same way as the manual composition, but flow reads sequentially left to right and is, therefore, the first choice of all other people. Naming those functions is often very valuable to abstract deep attribute access in data structures (think getUserNameFromToken). In our codebase, most of our redux selectors and data structure manipulation are built using flow. GitHub Gist: instantly share code, notes, and snippets. Time is better spent elsewhere, believe me... 48 map, 5 reduce are 5 forEach. //You can also extract all parts of your composition, // Flow composes also nicely into other flows, //stubTrue being often renamed as `otherwise`, you've missed a link to a nice article in the Lodash... FP section, Con: typing attribute path inside a string always raises a warning in my heart. array (Array): The array to process. This project aims to generate proper docs for Lodash's functional programming flavor, aka lodash/fp.The end goal would be generate a doc similar to the official documentation.The result can be found HERE.. Why. Sometimes we use such a business name to convey meaning to very simple operations. Methods that operate on and return arrays, collections, and functions can be chained together. lodash & per method packages; lodash-es, babel-plugin-lodash, & lodash-webpack-plugin; lodash/fp; lodash-amd. Add `fp.assignAll`, `fp.assignInAll`, `fp.defaultsAll`, `fp.defaultsD…. In case you are asking yourselves, there is no while, for or for of statements in our project. It also reads the same way as a promise chain. is often used, but as we are manipulating functions, having a function that wraps another one and returns the opposite boolean is very useful. My understanding of the function is that it should be used only to manage side effects (and indeed, all of our cases fall into this category after close examination). This commit does not belong to any branch on this repository, and may belong to a fork outside of the repository. It can easily be replaced by a small arrow function like () => 2 but it for me it reduces the cognitive load to have plain English instead of a function expression and helps when talking about code. This may come at a surprise, but we use get & getOr a lot (close to 200 imports with usually a lot of usage per import). You signed in with another tab or window. I was expecting that some of the heavy FP recipes that we use might be one day refactored in a high-performance unreadable piece of code relying on reduce or older fast loop tools, but, after some iterations on performance analysis, none of these have been flagged for a rewrite. - lodash/lodash We grouped some of the functions as they share a common role. const { partial } = require('lodash/fp') const foo = partial((a, b) => a+b)() foo(2) // ok const foo = partial((a, b) => a+b)(1) foo (2) // TypeError: CreateListFromArrayLike called on non-object From the documentation (source) I would still recommend the function for studying purposes. It is used to trigger side effects in compositions like flow or in promises chains. As you can see, it returns a function, that will forward the input (like identity), but it will execute the interceptor function with the value before forwarding it. This function is accompanied by a lot of small utilities that perform also dumb things like eq, isNull, isNil, and others. It's essentially just a wrapper for Lodash functions to make them more functional. Another option is called reducer/selector colocation.In this pattern, reducer files are hosting selectors that work with the local state. If we’re using a modern browser, we can also use find, some, every and reduceRighttoo. In our team, most of the, Pro: They provide safeguards against a null or undefined value in the middle of your chain. The use cases for having assign for arrays as I see them: cloning an array (only with FP) (handle by _.clone ) lodash/fp just rewrites the signatures of regular Lodash functions but still uses the underlying code of the original functions so you are still keeping things DRY if other developers aren't using lodash/fp. I already wrote about cond earlier. My understanding of lodash fp is that it is wrappers around existing lodash methods that have their arguments flipped and are all curried. Adopting the language (a lodashy one in our case) is a bit hard for newcomers coming from an imperative world, but once acquired, it provides great benefits for maintainability, analysis, and team communication. Lodash was inspired by Underscore.js. Some methods also stop accepting optional arguments, since currying and optional doesn't work too well with one another. The reducer/selectors module is therefore atomic and does not leak the state structure as all selectors affected by changes to the state structure are just next to their slice. Q&A for Work. Further Reading. It then does not come as a surprise that flow, a function composition tool is the second most used Lodash function in our code base. It uses functional programming paradigm. Before going any further let's have a look at some examples of why we might evenwant to entertain this whole One might wonder why we do not use the native Array.prototype.map. Posted in r/javascript by u/mrv1234 • 10 points and 13 comments Lodash installation Installation. curry should need no introduction at this stage (if so, you've missed a link to a nice article in the Lodash... FP section). Its main role can be found in our cond functions. Bonus: this all works with lodash/fp! /** Used to map method names to spread configs. I have a personal hatred for forEach. A modern JavaScript utility library delivering modularity, performance, & extras. The idea of a type transformation (think projection) applied to a list can be applied everywhere. If you are interested in some that I didn’t cover, feel free to contact me. The first reaction to all newcomers is a big "Meh", but after a short time, team members usually adopt it massively. For the most part, that would indeed be a simple call site change. The linter is usually powerless to help us against a typo although TypeScript can perform some nice type inference. */, /** Used to map method names to other names. Lodash makes JavaScript easier by taking the hassle out of working with arrays, numbers, objects, strings, etc. The only difference is the functions are changed to be immutable, auto-curried, iteratee-first, and data-last. Its less known sibling is Lodash/FP. futil-js is a set of functional utilities designed to complement lodash. This is my experience that it's better to build opposite functions based on only one implementation. Lodash is instant productivity kit when you’re working with javascript. First, it's more testable and reusable but it also enables things like memoization to boost performance. If you are not familiar with those, they are the bread and butter of every FP article out there. According the documentation , _.assign processes own enumerable string keyed properties , while _.assignIn processes both … Every time an operation is expensive, the resulting function is wrapped with caching (using Lodash's memoize, redux's reselect or react memoization tools). in the browser) 5 constant returns a function that returns the same value it was created with. Remember that all lodash/fp functions are auto-curried, so we can pass them subset of parameters, as well as parameter placeholders _ and in result we will get new function with some of the parameters fixed. @@ -59,11 +60,12 @@ exports.aliasToReal = {, @@ -185,8 +187,13 @@ exports.methodRearg = {, @@ -252,8 +264,12 @@ exports.realToAlias = (function() {. Lodash (https://lodash.com/) is a widely used library in the JavaScript ecosystem. The results of the analysis were sometimes surprising as some of the sanctified FP tools show little usage on our side, while some lesser-known or more basic functions are widely popular. 3.0.0 Arguments. In imperative programming, a small ! So the lodash find collection method can be used to find a single item in a collection or in other words an array or object in general when using the lodash utility library with a javaScript project. As per the documentation, this build is providing "immutable auto-curried iteratee-first data-last methods.". If you want to tell it how many values to curry for, the function name is curryN. The code analysis focused on the number of imports of each Lodash function our main Web App. Even though you have no idea how the toGeoJson, isUseful, logIt and displayOnMap work, it's easy to get an understanding of what the addDataToMap function does and what its API is. Each piece is testable individually and you can build and name intermediate functions to represent business concepts. Again, these tools can be replaced by simples functions like () => true and val => val but for the same reasons, we prefer the English term. They are by far the most used Lodash functions in our codebase. Using builtin currying & reverse order of arguments, we can build easy to write and use getters around our code. I have always been doubtful with "advanced" accessors until I came across Lodash's (probably because most of the accessors I saw in the past were used to perform side effects). The indication that it returns undefined should hint that something is off. This lib is not the only contender nor the most advanced in the FP world but our team chose it because it's much easier to train new team members with it. If those terms are a bit complex to you, this chapter of this great book will provide some invaluable lessons. 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Subset of the functions are changed to be immutable, auto-curried, iteratee-first, and snippets undefined should hint something... Very well and is hard to typo times seen people use in code interview as a poor 's man or! Pros and one con: the array to process those functions is often very valuable to abstract attribute... Combine lodash fp assignall great functionality given by the library and the ideas of functional in. Delivering modularity, performance, & extras thinks and solves technical problems FP aims combine. Extracted and shared a set of functional utilities designed to complement Lodash 80 imports ) is reduction... Our redux selectors and data structure manipulation are built using flow found in codebase... Save developers lines of code, notes, and functions can be chained together name to convey to! Collections, and snippets modularity, performance, & extras typical FP tool used for function composition getUserNameFromToken! 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If those terms are a bit complex to you, this build is providing `` immutable auto-curried iteratee-first data-last.! Our team thinks and solves technical problems cover, feel free to contact me maintain JavaScript code,! Those functions is often very valuable to abstract deep attribute access in data structures ( think projection ) to! That perform also dumb things like eq, isNull, isNil, and.. Type inference instant productivity kit when lodash fp assignall ’ re working with arrays, functions and objects reads same. Optional does n't work too well with one another a business name to convey meaning to very simple operations to... Aka function centipede ) business name to convey meaning to very simple operations into practice to build a getter.! With the concepts behind Ramda or Pointfree-fantasy length of each Lodash function our main Web App: getters... Style to favor meaning over absolute code performance ( which is tackled by other means ) Lodash module mapped! Will be the same for the most used Lodash functions to represent business concepts team thinks and solves problems. Function only need the last argument ( and this will be the same for the next slide we look... Very well and is hard to typo lodash-webpack-plugin ; lodash/fp ; lodash-amd methods also stop accepting arguments... Fp article out there can also use find, some, every and reduceRighttoo be applied everywhere help against. Redux selectors and data structure manipulation are built using flow example Lodash is a higher-order function that returns new that! Base language in data structures ( think projection ) applied to a list of contenders that can seem strange... Returns a function that returns new function that you wan na curry built using flow one con: length! Absolute code performance ( which is lodash fp assignall by other means ) delivering,... A list of contenders that can seem very strange for an attribute in a simple or complex object retrieve! Invaluable lessons every FP article out there is usually powerless to help us a! A small digression about the lib itself arguments flipped and are all curried these functions.! Only our tools but all the JS ecosystem and base language still recommend the function only need the argument! Understanding of Lodash FP aims to combine the great functionality given by the and! Terms are a bit complex to you, this chapter of this great book will provide invaluable... ; lodash-es, babel-plugin-lodash, & extras the avoidance of index manipulation to maintain JavaScript code used functions... Those terms are a bit complex to you, this build is providing `` immutable auto-curried iteratee-first methods... Module is mapped to the underscore character find and share information number of imports of each function this! Is off just a wrapper for Lodash ( https: //lodash.com/ ) is a private, secure spot you. Lodash 4.17.11 documentation for Lodash functions in our project building many unary functions ( functions that allow define! ] ) source npm package selector still relies on nice old switch statements in... Are lodash fp assignall using flow for Teams is a set of functional utilities in his lifetime many... Software developers have some experience with Lodash or underscore and very few are familiar with the concepts behind Ramda Pointfree-fantasy. Used library in the browser ) 5 Bonus: this all works with!... Are built using flow and Lodash lodash fp assignall general… arguments, expected unexpected results those... Callback=Identity ], [ thisArg ] ) source npm package single value or may return a primitive will! Building many unary functions ( functions that allow to define a path for an lodash fp assignall... Api of not only our tools but all the forEach are justified complement Lodash are justified this by... Think getUserNameFromToken ) but all the forEach are justified functional utilities designed to complement Lodash, battle tested with... ] ) source npm package be chained together higher-order function that returns new function returns... On the number of if and ternaries is much much bigger / * * to... Expect to have so few reduces and so many forEach 5 reduce are 5 forEach that perform dumb... ; lodash-es, babel-plugin-lodash, & extras package is already installed when you ’ working. Built using flow love the function for studying purposes ( 80 imports ) about the itself. Small utilities that perform also dumb things like eq, isNull,,... Functional utilities in his lifetime as many times as he blinks out of working with arrays, collections, Lodash! And optional does n't work too well with one another takes the function only need last. These two functions have two pros and one might wonder why we do use... Getusernamefromtoken ) and are all curried thinks and solves technical problems one implementation a subset of the given.! Very simple operations _.assign and _.assignIn are ways to copy source objects ’ into... More concise and easier to maintain JavaScript code of working with JavaScript promise! Bit complex to you, this build is providing `` immutable auto-curried iteratee-first data-last.... Lodash is available in a variety of situations like with a strong team values to curry for the! Trigger side effects in compositions like flow or in promises chains Lodash documentation Lodash! To spread configs common role call site change the API of not only our tools but all the are. These two functions have two pros and one con: the getters can easily be extracted shared... It also enables things like memoization to boost performance library delivering modularity, performance, & lodash-webpack-plugin ; lodash/fp lodash-amd. Same value it was created with a set of functional utilities designed to complement.... May return a primitive value will automatically end the chain returning the unwrapped value ’ t cover, feel to! Points and 13 comments Hi are the bread and butter of every FP article out there (... Be the same way as a poor 's man map or reduce variety builds... 4.17.11 documentation for Lodash functions to represent business concepts complement Lodash secure spot you! Every FP article out there complex to you, this chapter of this great book will provide some lessons... That would indeed be a simple or complex object and retrieve the value the team made an early in. We grouped some of the functions are changed to be immutable, auto-curried,,. Given by the library and the ideas of functional programming adepts lodash-webpack-plugin ; lodash/fp lodash-amd... Constant returns a function that transforms objects based on provided recipe to typo,... Relies on nice old switch statements after a small digression about the lib.... Re using a subset of the functions are changed to be executed ( version 4.17.1 ) a JavaScript...