The Difference Between a Callback Function and a Promise in Node JS

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A promise is like you're resolving a promise to do something when something has been complete. Instead of the callback function running when the function is complete, we're waiting for the results of the function to be complete and then accepting the results as they're returned from the function. So basically instead of calling a function when that function has completed to get the results, what we're doing is we're saying, hey, when this function has completed, then do this thing,. Whether it is the using a dot then to do the promise or using a single way to wait for the function to have completed.

In this episode of Syntax, Wes and Scott answer coding questions posed by ChatGPT like what’s the difference between rem and em in CSS, the difference between a callback function and a promse in Node, what are Fastify plugins, and more!

Show Notes

00:19 The premise for this Stump’d
05:46 Scott’s weekend story
09:36 What is the difference between a for loop and a while loop in JavaScript?
11:11 What is the difference between the “em” and “rem” units in CSS, and when would you use each of them?
13:15 What is the difference between a callback function and a promise in Node.js?
14:57 In JavaScript, what is the difference between a function declaration, a function expression, and an arrow function, and how do they affect the concept of hoisting?
18:39 How do you define a custom scalar type in GraphQL?
21:30 With Deno, can you provide an example of an experimental API that requires the “–unstable” flag and explain its purpose?
26:59 What’s the difference between a div and a span?
28:01 What is aspect ratio?
29:07 If it’s not supported by all browsers, how could you maintain aspect ratio?
30:11 Can you explain the purpose of the beforeUpdate lifecycle function in Svelte, and provide a simple use case for it?
32:33 What is the difference between unknown and any in TypeScript, and when should each be used?
34:42 In TypeScript, what is a mapped type, and how can you use it to create a new type that makes all properties of an existing type optional?
36:21 What are Fastify plugins, and how can they be used to extend the functionality of a Fastify application?
37:57 In React, what is the purpose of the React.memo higher-order component, and how does it help improve the performance of a functional component?
39:53 How would you create a custom HTML element that is styled with CSS and has dynamic behavior using JavaScript?
41:57 What is the Intersection Observer API, and how can you use it to implement infinite scrolling in a web application?
49:00 SIIIIICK ××× PIIIICKS ×××