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7 Useful Javascript Tips

Victor Chan on June 18, 2020

7 Useful Javascript Tips Without further ado, lets dive into it: Filtering falsy values: If you have an array of values, you can f...

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˗ˏˋトバーˎˊ˗ • Jun 19 '20

On the last one perhaps there is a formatting error, since comment is affecting the const declaration:

//Map and catch for promises 
//And just console.log them 
const all = await Promise.all(
    promiseArray.map(p => p.catch(console.log))
)

Victor Chan • Jun 20 '20

Thanks, I'll give it an edit!

Alex Vechy • Jun 20 '20

Thanks for sharing. It's good to know tricks even if it's not good to use them.
Example with implicit number coercion on Date is misleading. I'll be disappointed to see it in some produciton code.

new Date(+new Date() + 10 *1000)
// vs
new Date(Date.now() + 10 * 1000)

Victor Chan • Jun 21 '20

Ahh true, that looks much more understandable. Thanks for the feedback!

Tim West • Jun 18 '20

From my experience, 2, 3 & 5 aren't significantly faster and make the code harder to read/understand. I avoid these by enabling eslint rules to disable implicit coercion.

Tip 7 can soon be replaced by the new ES2020 Promise.allSettled() feature.

Victor Chan • Jun 19 '20

True, readability is a good point. Thanks for the feedback!

Jon Randy 🎖️ • Jun 19 '20

Shorter way to filter falsey values:

myArray.filter(x=>x)

veljko94pesic • Jun 19 '20

Maybe you should mention that double tilde operator (~~) for negative numbers acts like Math.ceil() function, in your example:

const x = -1.5
const y = ~~x

console.log(y) // Equals -1

Nice article btw :)

Victor Chan • Jun 19 '20

Awesome, didn't know about that. Thanks for sharing!

Mike Talbot ⭐ • Jun 18 '20

Nice - I learned one there. I've mostly used |0 to floor numbers but I like the ~~ prefix style a lot too. I like the parameter validation one too. That's nice.