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Change your old methods for writing a JavaScript Code - Shorthand's for JavaScript Code

Simc Dev on October 05, 2022

1. Shorthand for if with multiple OR(||) conditions if (car === 'audi' || car === 'BMW' || car === 'Tesla') { //code } Ent...

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Mohamed Mayallo • Oct 6 '22 • Edited

8. Shorthand to remove duplicates from array

Array.from(new Set([1, 2, 3, 1, 2]))

9. Shorthand to conditionally insert a key/value in an object

let isTrue = false;
let obj = {
    name: 'hello',
    ...(isTrue && { age: 30 })
}
console.log(obj)

Muhammad Sifat Hossain • Oct 6 '22

Thanks for the number 9. I already knew 1 to 8 but I never thought of using number 9 method.

Jon Randy 🎖️ • Oct 6 '22 • Edited

The two examples on number (3) are not equivalent. In more ways than one.

Other examples are also suffering similarly. Within each example, the code snippets should ideally be functionally equivalent in order to make a fair comparison.

Corey Scheideman • Oct 6 '22

If an arrow function looks too long on one line, just use parens or curly brackets.

// returns undefined
const logSomething = () => {
  console.log('Something')
}

// returns string
const getValue = (isX) => (
  isX ? 'x' : 'not x'
)

leob • Oct 6 '22

What is it with this if(amount === null) { syntax where people are omitting the space between the if and the (? I'm getting the impression that it's a trend, I see it more and more. Is it because "if()" is being seen as a function, or something?

Corey Scheideman • Oct 12 '22 • Edited

What do you mean "more common"? I see the form of what I've put here in my previous comment very very often. And in my opinion, pound for pound, it's really not much less readable than

// returns undefined
function logSomething() {
  console.log('Something')
}

// returns string
function getValue (isX) {
  return  isX ? 'x' : 'not x'
}

Although I'll admit, that I personally never use

function foo() { /* ... */ }

function() { /*...*/ }

inline inside of outer statements, but rather more often as standalone functions.

Corey Scheideman • Oct 12 '22 • Edited

Oh I see, fair point. I was thinking of JS in particular.

From my experience in Python,

foo = lambda x: print(x)

is indeed exceedingly rare compared to

def foo(x):
    print(x)

I guess because the former is probably just not "Pythonic". Inline lambda functions in python are imo ugly and much less readable because of their syntax and just not as typical as inline arrows are in JS, for good reason. I think these Python lambdas are only really supposed to be for quick and cheap one-liners where the function only runs a single statement and/or returns the value of it.

codingjlu • Oct 6 '22

I've been JavaScripting for a long time, but some things you said were invaluable. I love the conditional function one; I can't believe I've never thought of that before! The multiple condition one is also brilliant. Thank you!

Muhammad Sifat Hossain • Oct 6 '22

Nice tips. But I've a question about the number 1 (though I use it sometimes in my code). Seems like for every check it'll create a new array. Is that inefficient?

Jodi Winters • Oct 9 '22

Yes, but not likely for that reason. I did a quick crude benchmark and Firefox runs the includes-style check at almost 10x slower. Chrome runs them even slower, which is a point that implementations vary. You don't want to run code like that in a tight loop! I ran an extra check with the array creation outside the loop, it didn't improve speed by much. So it's not so much the creation of the new array, I suspect that can be optimised by runtime code compilers - it'll be the looping and checking in the includes method that takes time. I also use it in code, but I'll have to be mindful of where I use it. Alas, many shorthands are actually quite poor for optimisations.

Muhammad Sifat Hossain • Oct 10 '22

Thanks for the benchmark result. I'll also try to be mindful about it.

Corey Scheideman • Oct 13 '22 • Edited

All good. Makes sense :)

Hah! Yeah, I saw the term "Pythonic" thrown around in the Python community for a while. I particularly remember seeing it a fair bit on Stack Overflow in response to whenever someone posted something super hacky that would be fine in whatever language but there's a more natural and readable solution built into Python for better simple elegance or something like that.

Adam Crockett 🌀 • Oct 6 '22

4 would crash on a default case?

Jodi Winters • Oct 9 '22

No, it should return null. It would only crash if data didn't exist or wasn't an object. But in this case it's under your control so very unlikely. I don't know if strictmode modifies that behaviour, though. If you wanted default to return another value, when accessing it you would borrow from no. 3, i.e. data[num] || 'defaultValue'

Adam Crockett 🌀 • Oct 10 '22

Then I argue that, switch is for finite cases where all answers are known and default with no value being provided is an antipattern of switch which an object has no equivalent

Jodi Winters • Oct 11 '22

It might if it's a Map, but the code would be so fugly you might as well use a switch :D

Ebony Dominguez • Oct 11 '22

Thank you! Very useful tips. I am just starting to work with JavaScript, so this information is very valuable for me. In addition, I am now getting acquainted with various projects that use this language to see how it works in the system. Of the latter, I would like to mention SlotoGate. It was interesting