lrvick

// convert 0..255 R,G,B values to binary string
RGBToBin = function(r,g,b){
    var bin = r << 16 | g << 8 | b;
    return (function(h){
        return new Array(25-h.length).join("0")+h
    })(bin.toString(2))
}

// convert 0..255 R,G,B values to a hexidecimal color string
RGBToHex = function(r,g,b){

mikaelbr

// === Arrays

var [a, b] = [1, 2];
console.log(a, b);
//=> 1 2


// Use from functions, only select from pattern
var foo = () => [1, 2, 3];

yesvods

const arr1 = [1,2,3]
const arr2 = [4,5,6]
const arr3 = [...arr1, ...arr2] //arr3 ==> [1,2,3,4,5,6]

ljharb

Array Iteration

https://gist.github.com/ljharb/58faf1cfcb4e6808f74aae4ef7944cff

While attempting to explain JavaScript's reduce method on arrays, conceptually, I came up with the following - hopefully it's helpful; happy to tweak it if anyone has suggestions.

Intro

JavaScript Arrays have lots of built in methods on their prototype. Some of them mutate - ie, they change the underlying array in-place. Luckily, most of them do not - they instead return an entirely distinct array. Since arrays are conceptually a contiguous list of items, it helps code clarity and maintainability a lot to be able to operate on them in a "functional" way. (I'll also insist on referring to an array as a "list" - although in some languages, List is a native data type, in JS and this post, I'm referring to the concept. Everywhere I use the word "list" you can assume I'm talking about a JS Array) This means, to perform a single operation on the list as a whole ("atomically"), and to return a new list - thus making it mu

hilkeheremans

REACT NATIVE IOS vs ANDROID FONT USE

Tested for React Native 0.41+

IOS:
- Place the fonts in the assets and make sure they are bundled along
- On iOS, fontFamily in Text match the Font Family name as described in Font Book (macOS). Font weights can be specified exactly.

ANDROID:
On Android, there are two ways of using fonts:

praveenpuglia

I am moving this gist to a github repo so more people can contribute to it. Also, it makes it easier for me to version control.

Please go to - https://github.com/praveenpuglia/shadow-dom-in-depth for latest version of this document. Also, if you find the document useful, please shower your love, go ⭐️ it. :)

Shadow DOM

Heads Up! It's all about the V1 Spec.

In a nutshell, Shadow DOM enables local scoping for HTML & CSS.

andrescalco

"scripts": {
	"enable_local": "plutil -insert NSAppTransportSecurity -xml \"<dict><key>NSExceptionDomains</key><dict><key>localhost</key><dict><key>NSExceptionAllowsInsecureHTTPLoads</key><true/></dict></dict></dict>\" ios/myProject/Info.plist",
	"remove_local": "plutil -remove NSAppTransportSecurity ios/myProject/Info.plist"
},

slikts

Why using the children prop makes React.memo() not work

I've recently ran into a pitfall of [React.memo()][memo] that seems generally overlooked; skimming over the top results in Google just finds it mentioned in passing in a [React issue][regit], but not in the [FAQ] or API [overview][react-api], and not in the articles that set out to explain React.memo() (at least the ones I looked at). The issue is specifically that nesting children defeats memoization, unless the children are just plain text. To give a simplified code example:

const Memoized = React.memo(({ children }) => (<div>{children}</div>));
// Won't ever re-render
<Memoized>bar</Memoized>
// Will re-render every time; the memoization does nothing