Global Object Reflect In JavaScript

Brandon Roberts — Sun, 19 Apr 2020 17:23:55 +0000

As I was reading Axel's book on Generator functions I came across a new Global Object in Javascript that I never even knew existed!
Reflect

22.1.3 Use case: implementing iterables #
The objects returned by generators are iterable; each yield contributes to the sequence of iterated values. Therefore, you can use generators to implement iterables, which can be consumed by various ES6 language mechanisms: for-of loop, spread operator (...), etc.

The following function returns an iterable over the properties of an object, one [key, value] pair per property:

function* objectEntries(obj) {
    const propKeys = Reflect.ownKeys(obj);

    for (const propKey of propKeys) {
        // `yield` returns a value and then pauses
        // the generator. Later, execution continues
        // where it was previously paused.
        yield [propKey, obj[propKey]];
    }
}

This was interesting to me that there was this object available so I decided to start to research this more.

You can learn more about Reflect here.
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Reflect

A better way to turn strings into arrays!

Brandon Roberts — Wed, 01 Apr 2020 10:39:33 +0000

Converting a string to an array is quite a common occurrence for most developers. But I recently found a way to do this that is more concise and readable.

How most Javascript developers turn their strings into an array:

const name = "Brandon"
name.split("")
// Result: ["B", "r", "a", "n", "d", "o", "n"]

This works perfectly fine, and is actually the way I see 90%+ of developers covert their strings into an array.

The downside for me is, it's not extremely readable for people who don't know the ins and outs of the Array.split method.

The better way to turn your strings into arrays.

const name = "Brandon"
Array.from(name)
// Result: ["B", "r", "a", "n", "d", "o", "n"]

This produces the exact same result as Array.split(""), but here your code reads like a book. Array.from(your_string) is exactly what you want to do.

Performance

I did do some research on performance differences between these two ways of converting strings to an array.
I only found one non official blog saying that Array.split is considerably faster than Array.from, however I would be interested to read more tests on this before I'm convinced. If you can provide more info on this topic please leave a comment below.

Fun Fact

Another nice thing you can do is turn a Node List into an array, using Array.from.

const pTags = Array.from(document.querySelectorAll('p'));