DEV Community

loading...
Cover image for Top 20 JavaScript tips and tricks to increase your Speed and Efficiency

Top 20 JavaScript tips and tricks to increase your Speed and Efficiency

Kapil Raghuwanshi🖥 on June 08, 2021

Convenient and useful techniques to reduce the lines of code and pace up your Dev Work! In our daily tasks, we get to write functions su...
Collapse
martinmuzatko profile image
Martin Muzatko

min: Math.min(...numbers)
max: Math.max(...numbers)

Collapse
tomy profile image
Tomy Smith

Exactly, not sure of the advantage of using reduce over these common functions.

Collapse
andrewbridge profile image
Andrew Bridge

I'd go further and agree with this thread and follow up video that advise against using reduce in nearly every situation. It's often used when a simpler or more readable alternative is available, and leads to harder to read, harder to maintain code. As proven with this example above.

Collapse
techygeeky profile image
Kapil Raghuwanshi🖥 Author

Well, of course above methods seems simpler for finding min/max but one should not underestimate the power of reduce in JavaScript. There are several technique where you can solve problems mostly in one reduce statements only.

Thread Thread
erasmuswill profile image
Wilhelm Erasmus

But in this case a helper method that does the full job exists so why bother with reduce for this use case? I admittedly do not use it enough but just saying

Collapse
liquorburn profile image
liquorburn • Edited

I've made a simple benchmark, it seems that reduce() is faster than Math.max()

dev-to-uploads.s3.amazonaws.com/up...

Thread Thread
techygeeky profile image
Kapil Raghuwanshi🖥 Author

That's awesome @liquorburn . I have added the fastest one only.

Thread Thread
tomy profile image
Tomy Smith • Edited

It's actually the spread operator that's taking the time there. Though admittedly, there aren't many cases you'd have a hardcoded list of values to find the max of, it's worth pointing out.

dev-to-uploads.s3.amazonaws.com/up...

Collapse
techygeeky profile image
Kapil Raghuwanshi🖥 Author • Edited

Thanks for reminding this tip @martinmuzatko .

const array = [4,5,7,2,3];
Math.min(...array)
// Output: 2
Math.max(...array)
// Output: 7
Enter fullscreen mode Exit fullscreen mode
Collapse
boydevelopr profile image
FredDev

Please what tool is used to make this code snippet embedment on the pages?

Thread Thread
techygeeky profile image
Kapil Raghuwanshi🖥 Author

These are just code test only. Use 3 backticks before and after your code. Check the preview.

Collapse
lexlohr profile image
Alex Lohr

About the logical operators in 5, you should always be aware of their defined behavior:

  • a && b yields b if a is truthy, otherwise false
  • a || b yields the first value of a, b that is truthy

This means that a || b && c will return a if it a is truthy. If you are using a tool like prettier, you can just use brackets everywhere and let it figure out where they can be removed safely.

Collapse
techygeeky profile image
Kapil Raghuwanshi🖥 Author • Edited

I second that @lexlohr ! Nice suggestion to keep in mind.

Collapse
snigo profile image
Igor Snitkin

Looks more like “Hey, I know a bit of JS” rather than tips really. Let’s start with one, can you think of a way to make the matrix in a bit more efficient manner (hint: 2 iterations less), so it starts looking like a tip that will make me more efficient as advertised

Collapse
techygeeky profile image
Kapil Raghuwanshi🖥 Author

Well thanks for the comment @snigo . And I didn't want to sound like “Hey, I know a bit of JS”, if I did, share the points/sentences, will try to fix them.
However, as I pointed out earlier in the post that - there can be more than one approaches to the same problem, so feel free to share yours here.

Collapse
snigo profile image
Igor Snitkin

Enjoy:

const matrix = (x, y = x, fillValue = 0) => Array.from({ length: y }, () => Array(x).fill(fillValue));
Enter fullscreen mode Exit fullscreen mode

Now, number two: what's going to be the sum of an empty array in your example?

Thread Thread
techygeeky profile image
Kapil Raghuwanshi🖥 Author

How about these two?

const arr = Array.from(Array(4).fill('O'), () => new Array(4).fill('O'));
Enter fullscreen mode Exit fullscreen mode
const arr = [...Array(8)].map(() => Array(8).fill("0"))
Enter fullscreen mode Exit fullscreen mode
Thread Thread
snigo profile image
Igor Snitkin • Edited

If we talk about efficiency, then we first need to figure out .map or .from:

  • map: maps over elements returning new array 👎
  • from: mapFn maps over elements in place 👍

So from, which leaves us with the question what we're going to create our array from, right? So if we compare:

// Array from array
Array.from(Array(3), () => Array(3).fill(0));

// Array from object
Array.from({ length: 3 }, () => Array(3).fill(0));
Enter fullscreen mode Exit fullscreen mode

...it will boil down to the question what's more efficient to create Array(3) or { length: 3 }, and given arrays in JS are just objects it really comes to the number of properties we need to create for the object. How many properties does Array(3) have? (hint: 4) How many properties does { length: 3 } have? (hint: 1)

I hope this will clear things a bit

Thread Thread
techygeeky profile image
Kapil Raghuwanshi🖥 Author

Awesome and detailed explanation @snigo . ✌🏻
I have created GitHub Repo, feel free to contribute to that.
Thanks!🤗

Collapse
manoharreddyporeddy profile image
Manohar Reddy Poreddy

Cool
Have a github too so other can collab.
Also fix the bug in

return temp > 97 ? 'Visit Doctor!'
      : temp < 97 ? 'Feel Better!'
      : temp === 97 ? 'Take Some Rest!'
      : 'Go Out and Play!';
Enter fullscreen mode Exit fullscreen mode
Collapse
techygeeky profile image
Kapil Raghuwanshi🖥 Author

Thanks @manoharreddyporeddy . Astonishing Idea of GitHub. Will create the repo and update the link in the post itself for further collaboration.

Nevertheless, what error are you pointing out in above snippet?

Collapse
manoharreddyporeddy profile image
Manohar Reddy Poreddy
return temp > 97 ? 'Visit Doctor!'
      : temp < 97 ? 'Feel Better!'
      : temp === 97 ? 'Take Some Rest!'
      : 'Go Out and Play!';
Enter fullscreen mode Exit fullscreen mode

can be

return temp > 97 ? 'Visit Doctor!'
      : temp < 97 ? 'Feel Better!'
      : 'Take Some Rest!' ;
Enter fullscreen mode Exit fullscreen mode

OR

return temp > 97 ? 'Visit Doctor!'
      : temp < 97 ? 'Feel Better!'
      : 'Go Out and Play!';
Enter fullscreen mode Exit fullscreen mode

Reason is a number can only be < or > or === 97.
There can't be a 4th option.

Hope it's clear now.
Will wait for your github link.

Thread Thread
techygeeky profile image
Kapil Raghuwanshi🖥 Author

Oh I got that one now! Updated.

Here is the link for the GitHub repo, github.com/kapilraghuwanshi/quick-.... Need to finalize the repo structure and PR etc, if you have suggestions please add to that repo.

Collapse
adirtyshame profile image
Thomas • Edited

Looks like the classic FizzBuzz test

Collapse
rockson profile image
Rok Zigon
   arg1 = arg1 || 10; 
// set arg1 to 10 as a default if it’s not already set 
Enter fullscreen mode Exit fullscreen mode

Comment should warn that if you use || to provide some default value, you may encounter unexpected behaviors if you consider some falsy values as usable (e.g., '' or 0).

Collapse
erasmuswill profile image
Wilhelm Erasmus

You're making me relive production drama right here :(

Collapse
bugb profile image
bugb • Edited

Unfortunately, in the real life, data are much more complex, I think if you can share about how to composite functions then it should be very helpful.

My tips

const string = 'kapilalipak';
[...string].reduce((m,n)=>({...m,[n]:-~m[n]}),{})
// {"k":2,"a":3,"p":2,"i":2,"l":2}

Enter fullscreen mode Exit fullscreen mode
Collapse
pazka profile image
Alexandre Weisser

I would advise to not use nested ternary operators as it is considered a code smell

Collapse
techygeeky profile image
Kapil Raghuwanshi🖥 Author

Can you share the disadvantages with code snippets ?

Collapse
pazka profile image
Alexandre Weisser

Sorry I don't have the time nor the patience at the moment but I can at least detail my answer :

Simply, if you think about the Signal-to-Noise ratio, nesting ternary operator will more often lead to error when sigh treading and ask more energy to be understood for the sake of a very few line of code.

In this particular case, writing a more explicit comparison will be better for the whole understanding of the code flow. with "ifs" or juste split it in more lines of ternary attribution.

Also, if you should write half a dozen comparison for the attribution of a variable, you should put it in a specific function that will be named accordingly and this will greatly improve this part of the code.

For more information, you can look in the ESLint documentation for this specific code smell : eslint.org/docs/rules/no-nested-te...

Also thank you for your post !

Collapse
erasmuswill profile image
Wilhelm Erasmus

Good article man, I just have a couple of comments further to the above:

6: I believe this approach only works if you are using strings or numbers, not objects

17: Earlier today, I learned that parseInt can also be used in this way. The second argument defines the number system base

Collapse
qq449245884 profile image
qq449245884

Dear Kapil Raghuwanshi,may I translate your article into Chinese?I would like to share it with more developers in China. I will give the original author and original source.

Collapse
techygeeky profile image
Kapil Raghuwanshi🖥 Author

Sure @qq449245884 , go ahead and share the GitHub link too, besides the article to contribute.

Collapse
qq449245884 profile image
qq449245884

ok,than you very much!

Collapse
kiranrajvjd profile image
Kiran Raj R

Just add "javascript" after your opening code block backticks for syntax highlighting.

Collapse
techygeeky profile image
Kapil Raghuwanshi🖥 Author

Thanks @kiranrajvjd for the tip. Updated to make it more colourful!

Collapse
mohammadmesbaulhaque profile image
Mesbaul Haque

Thanks bro...

Collapse
techygeeky profile image
Kapil Raghuwanshi🖥 Author

All my pleasure @mohammadmesbaulhaque !

Collapse
vladimirc profile image
Vladimir C

Never use ternary operators to replace more than a single if...else. Otherwise, it quickly becomes unreadable and error-prone. The example from your post is an excellent proof of this :'D

Collapse
youpiwaza profile image
max

Pretty gorgeous recap, definitly a must have for hackatons & dailycoding, thanks a lot !

Collapse
techygeeky profile image
Kapil Raghuwanshi🖥 Author

Thanks @youpiwaza . I have written for the same aim.

Collapse
joshternyak profile image
Josh Ternyak

Your post is well-written! I just launched a site bitcoinforecast.io and I developed it myself using ES6 JS. Your post covers the strategies I used to built the app. Keep up the great work Kapil.

Collapse
techygeeky profile image
Kapil Raghuwanshi🖥 Author

Thanks @joshternyak . 😀

Collapse
reememad profile image
ReemEmad

really amazing and helpful, thank u!!

Collapse
raulcg profile image
RaulC-G

2D matrix: Array(5).fill(Array(5).fill(0))

Collapse
techygeeky profile image
Kapil Raghuwanshi🖥 Author

@raulcg More crispier one!👍🏻