Certainly, here are some common bad practices in JavaScript that you should avoid to write clean, maintainable, and efficient code:
- Using Global Variables: Relying heavily on global variables can lead to naming conflicts, unintended data modification, and difficulty in debugging and maintaining code.
// Global variable
var globalCounter = 0;
function incrementCounter() {
globalCounter++;
console.log(globalCounter);
}
// Avoid global variables
function incrementCounter(counter) {
counter++;
console.log(counter);
return counter;
}
let localCounter = 0;
localCounter = incrementCounter(localCounter);
- Not Using Proper Variable Declaration: Always declare variables with
var,let, orconstto avoid polluting the global scope and to ensure proper scoping.
//Bad Practice: Using var instead of const/let
var count = 0;
//Better Practice
let count = 0; // Use let or const based on reassignment
const MAX_COUNT = 10; // Use const for constants
- Not Handling Errors: Failing to handle errors can lead to unexpected crashes or issues in your application. Always use try-catch blocks or promises to handle potential errors gracefully.
// Not handling errors
try {
// Code that might throw an error
} catch (error) {
// No error handling
}
// Handling errors
try {
// Code that might throw an error
} catch (error) {
console.error("An error occurred:", error);
}
- Callback Hell: Nesting callbacks excessively (also known as callback hell) can make code difficult to read and maintain. Consider using promises, async/await, or libraries like
async.jsto manage asynchronous operations more elegantly.
asyncFunction1(() => {
asyncFunction2(() => {
asyncFunction3(() => {
// More nested callbacks
});
});
});
//Better Practice
asyncFunction1()
.then(() => asyncFunction2())
.then(() => asyncFunction3())
.then(() => {
// Code after all async operations
})
.catch((error) => {
console.error("An error occurred:", error);
});
- Not Using "strict" Mode: Not using strict mode can lead to subtle bugs. Enable strict mode by adding "use strict"; at the beginning of your script or function.
6.Ignoring Semicolons: While JavaScript allows optional semicolons, it's a good practice to include them. Omitting semicolons can lead to unexpected behavior due to automatic semicolon insertion
const message = "Hello"
console.log(message)
//Better Practice
const message = "Hello";
console.log(message);
7.Using == Instead of ===: Always use strict equality (===) instead of loose equality (==) to avoid type coercion and unexpected comparison results.
if (value == 10) {
// This could lead to unexpected type coercion
}
if (value === 10) {
// Use strict equality to avoid type coercion
}
Top comments (24)
Hey, this article seems like it may have been generated with the assistance of ChatGPT.
We allow our community members to use AI assistance when writing articles as long as they abide by our guidelines. Could you review the guidelines and edit your post to add a disclaimer?
Guidelines for AI-assisted Articles on DEV
Erin Bensinger for The DEV Team ・ Dec 19 '22
The
use stricttip is actually bad practice. The strict mode should not clutter your code - this is something that either the build tooling (e.g., webpack, vite, ...) adds to your bundle or that your file has implicitly (you should use ESM - and these are strict by default).did you just copy paste from chat gpt?
yes, some of the snippet but before you copy from that you have go through of code of conduct of dev to
It's ok to use gpt but like someone says it's mediocre content, I'd you're using gpt atleast make advance stuff that's worth so many peoples time... hope to see good work from you
Type coercion is often extremely useful. I will never understand why developers are not keen to embrace some parts of JS. Use
==or===as appropriate, don't always favour one over the other.Hi Jon,
Would you also agree there are times (although few) when
varis a more appropriate declaration mechanism thanconstorlet?I think many of the points given above are valid but it can be less than helpful to have blanket statements such as 'x is bad, y is good'.
There are exceptions to every rule.
When would
varbe better? ... I never missed it, so I wonder.Consider the case when a variable is initialised (not declared) in one scope and used in another. In order to achieve this with
letthe variable has to be declared outside of both scopes and this means it will exist in the Temporal Dead Zone (TDZ) until it gets initialised. This can be avoided by usingvarto declare the variable at the point of initialisation. Because the variable will have 'function scope' it will still be accessible in the subsequent scope. Here is a very contrived example and I accept this might not be the best justification.The
letandconstkeywords have their use but they are not complete replacements forvar, only more appropriate in some case, just like==and conventional functions.Point
I appreciate your work! These are very useful suggestions.
I wonder, what are the benefits of using promises, async/await, or libraries like async.js over nested callbacks? I mean apart from coding style. Is there any performance benefit too?
I'm glad you find the information helpful! Moving from nested callbacks to using constructs like Promises, async/await, and libraries like async.js offers several benefits beyond just improving code readability and style. While the primary advantages might not always be related to performance, there can be some performance benefits as well.
dev.to/ikamran01/enhancing-asynchr...
Can I just point out that this is exactly what comes out when you ask chat gpt the question? Right down to the certainly, I use ChatGPT enough to get the feeling that this is what comes out when you propose the question to it.
Rather than make this personal, does this not seem ethically questionable to anyone? Are ChatGPT wrriten articles something we should be encouraging, or at least acknowledging? Can I become a writer with a following by thinking up questions, asking ChatGPT, and C/P it and pass it off as my own and people would be fine with that?
This isn't about the person who wrote the article nor any of the points, this is about the very quick effects of having a service that produces cookie cutter revenue for people without requiring a disclosure or even anyone else questioning it, and if the poster did happen to write this themselves, then sorry I apolgize for the implication. But this is one of the big ethical questions of how accepting we should be of AI, and why it's important we tackle this now before its too late and we're all ChatGPT.
ok bro understand your but if anyone has lack of time and and writting have to publish that,
one thing that why devloper use stackoverflow to copy past thare may snappit website are buit to make work easy and take less time why ? why evey one follow chatgpt most of the time and why it still going why pepople use it to for genrating content why its not stope since it started
bro keep your hate aside and i am giving this tip to make pepole aware what is that proble in this ??
hate is easey but support is not prety easy to get .
and you everywhere criticise me use that gentation snappit yes i use becous i didn't have to write that
ok i love your hate bro
nice to meet you
Point was made, reputation is everything when it comes to technical writing and professional expertise. The world isn't always fair but it's on every individual around the globe to maintain some sense of ethical standards. With all the division and mistrust in the world, it's imperative now more than ever to try to take the high road when possible.
Great post, thank you. It's important to have this type of guides to be aware of the practices that may be affecting our process and results.
most welcome dear stay connected for such type post and guides
the guy just asks ChatGPT a question and copy and pastes it. I spotted it and made it as impersonal as possible and as you can see, my post has been taken down by the author. Don't know what your actual business is, or if theres some connection or something, but the hypocrisy with people saying not to worry about AI replacing people, using AI to replace other people's knowledge without the work ethic to even make it look good, that happens to be one of my trigger points.
If you're in on the game, shame on ya, if you're independent and were makin an honest comment, I'd cut ties with this guy, he made it personal with me and I'd hate to have to do reputational harm to someone who didnt deserve it.
I say this not to you really, but anyone who is boosting this guy, they've made an enemy with alot of time on their hands and enough of a moral compass to not be a total hypocrite (not saying im a perfect person but I understand right from wrong and can attest to the consciousness of guilt of this dude, who's going to be the reason that AI becomes just another terrible addition to the zeitgest),
Excellent post! Hit some of the most crucial language practices that people need to know about when working with JS.
that really great to know than you
hey all of you can connet with me via twitter Twitter we will have sapace there get to learn more
thanks all
Thank you Kamran Ahmad!
It was very helpfull!
Pablo
most welcome and feel great to know this
Some comments may only be visible to logged-in visitors. Sign in to view all comments.