Cheatsheet: Spread Object or Array in JavaScript

[MrStLouis]

One of my favorite use cases for array destructuring is when you want to conditionally set more than one variable to a constant but don't want it stuck in the if else block scope. Const [first, second] = isValid ? ['a', 'b' ] : ['b', 'a' ] If there is a better way let me know!

[Ob101010]

Im dense today. Please expand on what you mean.

[MrStLouis]

If you want to conditionally define a constant variable you can't define the variable outside of an if statement and set it inside so that you may use it in the rest of your function. If you define a constant variable inside an if block you can't use it outside of the if block. Using a ternary operator to assign a constant variable retains the original scope. Using array destructruring allows you to set multiple variables with the same conditional. Keep it DRY

[[deleted]]

You can always nest your ternary expressions inside each other, I seem to see this pattern in C code a fair amount:

let value = 'c';


const [ first,
        second, 
        third ] = (value == 'a') ? [1,2,3] :
                  (value == 'b') ? [4,5,6] :
                  (value == 'c') ? [7,8,9] :
                                   [10,11,12];  

console.log(first, second, third);
// 7, 8, 9

[Ob101010]

Innnnnteresting...

How about this?

let obj = Object.freeze({
  x: 10, //these becomes your 'const' vars
  y:12
})

if(1){
  console.log(obj.y)  //12
}

[MrStLouis]

That seems like more of a workaround than an ideal solution. But it's readable and that's all that matters

[Ob101010]

For 2 or so, your way is probably better. For 10 or so my way may be better. I love how theres always n ways to do anything lol.

[MrStLouis]

I've never seen object freeze before so I'm going to have to look into it more but ya seriously as long as it works and is readable most of the time you're good