Those of you who know me know I have an absolute crap memory. Anything short of Monty Python dialog and track listing from a 90s alt rock band and I am dead to rights. Fortunately for us, however, computers are far more competent when it comes to remember things.
The Concept
The technique we are looking at today is called memoization. Let's start by discussing pure functions. The idea behind a pure function is that, no matter what input you give it, it is always going to give the same output. Now consider if you have a process intensive function or one that requires a lot of overhead. If you already know the result of running the function when provided a certain set of parameters why utilize your resources to run it again. Memoization allows us to store the result of a previous execution of a function using the parameters to that function as the key. The following code snippet demonstrates what a memoized function might look like:
The Execution
const memoize = {}; const getResult = async (n1, n2) => { const key = `${n1}_${n2}`; if (!memoize[key]) { memoize[key] = await resourceIntensiveFunction(n1, n2); } return memoize[key]; };
Let's take a look at the code. We start with an object called memoize that will store our parameters and the results as a key value set. Next we have our function called getResult that takes two parameters: n1 and n2. For simplicity's sake of this let's assume that the order matters. We are going to create a variable key using the concatenation of the two parameters.
Now we need to check to see if the memoize object contains a value for that key. We check and, if it doesn't, we have no choice but to run the resource intensive function. If we run the function we must also store the results in the memoization object for future execution. This way the next time run this function for these same parameters it'll find the result in the object and skip the resource intensive function.
Memoize when query has been previously run
Memoize when query has not been previously run
The Benefits
This can be useful in a number of scenarios. If, for instance, you have a long series of calculations that take an extensive amount of time and resource this good be a worthwhile optimization. It can also be valuable if you have something that requires high network throughput or a lot of temporary disk space. For any of these scenarios the advantage is two fold: It eliminates the need to run functions that have been previously executed and it frees up resources for those that need to be calculated because they aren't competing for resources with those functions that are already mapped.
The Challenges
There are situations where this might not be the right approach so don't always use this paradigm. If your function is not a pure function and it changes based on external factors then you don't want to use this approach as it'll always give you the values from the first run not taking into consideration those other variables. You also don't want to use this if the application will rarely run the function with the same set of parameters. In that case you'll have an increasingly large data structure that rarely gets used.
That's pretty much it for memoization. It's a pretty simple pattern with a very intimidating sounding name. There are a lot of applications for it and, hopefully, this gives you a better idea of what is happening under the hood. Now, if you'll excuse me, I have to go remember what it was I was going to do this evening.
Source code available on GitHub
The above is the detailed content of Thanks for the Memoize. For more information, please follow other related articles on the PHP Chinese website!

Detailed explanation of JavaScript string replacement method and FAQ This article will explore two ways to replace string characters in JavaScript: internal JavaScript code and internal HTML for web pages. Replace string inside JavaScript code The most direct way is to use the replace() method: str = str.replace("find","replace"); This method replaces only the first match. To replace all matches, use a regular expression and add the global flag g: str = str.replace(/fi

This tutorial shows you how to integrate a custom Google Search API into your blog or website, offering a more refined search experience than standard WordPress theme search functions. It's surprisingly easy! You'll be able to restrict searches to y

So here you are, ready to learn all about this thing called AJAX. But, what exactly is it? The term AJAX refers to a loose grouping of technologies that are used to create dynamic, interactive web content. The term AJAX, originally coined by Jesse J

This article series was rewritten in mid 2017 with up-to-date information and fresh examples. In this JSON example, we will look at how we can store simple values in a file using JSON format. Using the key-value pair notation, we can store any kind

Leverage jQuery for Effortless Web Page Layouts: 8 Essential Plugins jQuery simplifies web page layout significantly. This article highlights eight powerful jQuery plugins that streamline the process, particularly useful for manual website creation

Core points This in JavaScript usually refers to an object that "owns" the method, but it depends on how the function is called. When there is no current object, this refers to the global object. In a web browser, it is represented by window. When calling a function, this maintains the global object; but when calling an object constructor or any of its methods, this refers to an instance of the object. You can change the context of this using methods such as call(), apply(), and bind(). These methods call the function using the given this value and parameters. JavaScript is an excellent programming language. A few years ago, this sentence was

jQuery is a great JavaScript framework. However, as with any library, sometimes it’s necessary to get under the hood to discover what’s going on. Perhaps it’s because you’re tracing a bug or are just curious about how jQuery achieves a particular UI

This post compiles helpful cheat sheets, reference guides, quick recipes, and code snippets for Android, Blackberry, and iPhone app development. No developer should be without them! Touch Gesture Reference Guide (PDF) A valuable resource for desig


Hot AI Tools

Undresser.AI Undress
AI-powered app for creating realistic nude photos

AI Clothes Remover
Online AI tool for removing clothes from photos.

Undress AI Tool
Undress images for free

Clothoff.io
AI clothes remover

AI Hentai Generator
Generate AI Hentai for free.

Hot Article

Hot Tools

Safe Exam Browser
Safe Exam Browser is a secure browser environment for taking online exams securely. This software turns any computer into a secure workstation. It controls access to any utility and prevents students from using unauthorized resources.

SublimeText3 Linux new version
SublimeText3 Linux latest version

SublimeText3 Chinese version
Chinese version, very easy to use

Notepad++7.3.1
Easy-to-use and free code editor

SublimeText3 Mac version
God-level code editing software (SublimeText3)
