Amit Kumar amit08255

TypeScript Cheatsheet

Extracting and reusing return type of a function

declare function f1(): { a: number; b: string };
 
type T0 = ReturnType<() => string>;
type T1 = ReturnType<(s: string) => void>;
type T2 = ReturnType&lt;() =&gt; T&gt;;

HTML5 Form Validation Tricks

Disable submit button if any input HTML5 validations failed

form.validated-forms:invalid {
  button[type="submit"]:not(:disabled) {
    opacity: 0.5;
    pointer-events: none;
 }

Fix React Hydration Errors

Remove content from initial render (WORKS BEST)

export default function NoFirstRender({ theDate }) {
	const [hydrated, setHydrated] = React.useState(false);
	React.useEffect(() => {
		// This forces a rerender, so the date is rendered
 // the second time but not the first

SQL Cheatsheet

Get all columns in rows by distinct value in one column

select distinct on (category) * from "TargetGoal";

Select a column as boolean

RXJS CheatSheet

Basic Concept

The essential concepts in RxJS which solve async event management are:

Observable: represents the idea of an invokable collection of future values or events.
Observer: is a collection of callbacks that knows how to listen to values delivered by the Observable.
Subscription: represents the execution of an Observable, is primarily useful for cancelling the execution.
Operators: are pure functions that enable a functional programming style of dealing with collections with operations like map, filter, concat, reduce, etc.

I use GM to render thumbnails of png and jpg images.

Sadly the GM installation guide doesn't describe how to get things working on AWS EC2.

http://www.graphicsmagick.org/INSTALL-unix.html

Prepare for installing GraphicsMagick

These cheatsheet works for JSON-Generator

Using Custom Function For Final Data Result

[
  {
    data: [
      '{{repeat(15, 45)}}',
 {

Docker CheatSheet

Connect to postgreSQL using terminal

Docker compose example with postgreSQL:

version: "3"
services:
 # Postgres

	function interceptNetworkRequests(ee) {
	const open = XMLHttpRequest.prototype.open;
	const send = XMLHttpRequest.prototype.send;

	const isRegularXHR = open.toString().indexOf('native code') !== -1;


	// don't hijack if already hijacked - this will mess up with frameworks like Angular with zones
	// we work if we load first there which we can.
	if (isRegularXHR) {


	var exec = require('child_process').exec;
	var fs = require('fs');
	var util = require('util');
	var http = require('http');
	var url = require('url');
	var PDFDocument = require('pdfkit'); // http://pdfkit.org/


	http.createServer(function (req, res) {