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Quasar RAT Disguised as an npm Package for Detecting Vulnerabilities in Ethereum Smart Contracts
Socket researchers uncover a malicious npm package posing as a tool for detecting vulnerabilities in Etherium smart contracts.
rxjs-hooks
Advanced tools
Using npm:
$ npm i --save rxjs-hooks rxjs
Or yarn:
$ yarn add rxjs-hooks rxjs
import React from "react";
import ReactDOM from "react-dom";
import { useObservable } from "rxjs-hooks";
import { interval } from "rxjs";
import { map } from "rxjs/operators";
function App() {
const value = useObservable(() => interval(500).pipe(map((val) => val * 3)));
return (
<div className="App">
<h1>Incremental number: {value}</h1>
</div>
);
}
import React from "react";
import ReactDOM from "react-dom";
import { useEventCallback } from "rxjs-hooks";
import { map } from "rxjs/operators";
function App() {
const [clickCallback, [description, x, y]] = useEventCallback((event$) =>
event$.pipe(
map((event) => [event.target.innerHTML, event.clientX, event.clientY]),
),
["nothing", 0, 0],
)
return (
<div className="App">
<h1>click position: {x}, {y}</h1>
<h1>"{description}" was clicked.</h1>
<button onClick={clickCallback}>click me</button>
<button onClick={clickCallback}>click you</button>
<button onClick={clickCallback}>click him</button>
</div>
);
}
useObservable
export type InputFactory<State> = (state$: Observable<State>) => Observable<State>
export type InputFactoryWithInputs<State, Inputs> = (
state$: Observable<State>,
inputs$: Observable<RestrictArray<Inputs>>,
) => Observable<State>
export function useObservable<State>(inputFactory: InputFactory<State>): State | null
export function useObservable<State>(inputFactory: InputFactory<State>, initialState: State): State
export function useObservable<State, Inputs>(
inputFactory: InputFactoryWithInputs<State, Inputs>,
initialState: State,
inputs: RestrictArray<Inputs>,
): State
import React from 'react'
import ReactDOM from 'react-dom'
import { useObservable } from 'rxjs-hooks'
import { of } from 'rxjs'
function App() {
const value = useObservable(() => of(1000))
return (
// render twice
// null and 1000
<h1>{value}</h1>
)
}
ReactDOM.render(<App />, document.querySelector('#app'))
With default value:
import React from 'react'
import ReactDOM from 'react-dom'
import { useObservable } from 'rxjs-hooks'
import { of } from 'rxjs'
function App() {
const value = useObservable(() => of(1000), 200)
return (
// render twice
// 200 and 1000
<h1>{value}</h1>
)
}
ReactDOM.render(<App />, document.querySelector('#app'))
Observe props change:
import React from 'react'
import ReactDOM from 'react-dom'
import { useObservable } from 'rxjs-hooks'
import { of } from 'rxjs'
import { map } from 'rxjs/operators'
function App(props: { foo: number }) {
const value = useObservable((_, inputs$) => inputs$.pipe(
map(([val]) => val + 1),
), 200, [props.foo])
return (
// render three times
// 200 and 1001 and 2001
<h1>{value}</h1>
)
}
ReactDOM.render(<App foo={1000} />, document.querySelector('#app'))
ReactDOM.render(<App foo={2000} />, document.querySelector('#app'))
useObservable with state$
import React from 'react'
import ReactDOM from 'react-dom'
import { useObservable } from 'rxjs-hooks'
import { interval } from 'rxjs'
import { map, withLatestFrom } from 'rxjs/operators'
function App() {
const value = useObservable((state$) => interval(1000).pipe(
withLatestFrom(state$),
map(([_num, state]) => state * state),
), 2)
return (
// 2
// 4
// 16
// 256
// ...
<h1>{value}</h1>
)
}
ReactDOM.render(<App />, document.querySelector('#root'))
useEventCallback
import React from 'react'
import ReactDOM from 'react-dom'
import { useEventCallback } from 'rxjs-hooks'
import { mapTo } from 'rxjs/operators'
function App() {
const [clickCallback, value] = useEventCallback((event$: Observable<React.SyntheticEvent<HTMLButtonElement>>) =>
event$.pipe(
mapTo(1000)
)
)
return (
// render null
// click button
// render 1000
<>
<h1>{value}</h1>
<button onClick={clickCallback}>click me</button>
</>
)
}
ReactDOM.render(<App />, document.querySelector('#app'))
With initial value:
import React from 'react'
import ReactDOM from 'react-dom'
import { useEventCallback } from 'rxjs-hooks'
import { mapTo } from 'rxjs/operators'
function App() {
const [clickCallback, value] = useEventCallback((event$: Observable<React.SyntheticEvent<HTMLButtonElement>>) =>
event$.pipe(
mapTo(1000)
),
200,
)
return (
// render 200
// click button
// render 1000
<>
<h1>{value}</h1>
<button onClick={clickCallback}>click me</button>
</>
)
}
ReactDOM.render(<App />, document.querySelector('#app'))
With state$:
import React from "react";
import ReactDOM from "react-dom";
import { useEventCallback } from "rxjs-hooks";
import { map, withLatestFrom } from "rxjs/operators";
function App() {
const [clickCallback, [description, x, y, prevDescription]] = useEventCallback(
(event$, state$) =>
event$.pipe(
withLatestFrom(state$),
map(([event, state]) => [
event.target.innerHTML,
event.clientX,
event.clientY,
state[0],
])
),
["nothing", 0, 0, "nothing"]
);
return (
<div className="App">
<h1>
click position: {x}, {y}
</h1>
<h1>"{description}" was clicked.</h1>
<h1>"{prevDescription}" was clicked previously.</h1>
<button onClick={clickCallback}>click me</button>
<button onClick={clickCallback}>click you</button>
<button onClick={clickCallback}>click him</button>
</div>
);
}
const rootElement = document.getElementById("root");
ReactDOM.render(<App />, rootElement);
A complex example: useEventCallback with both inputs$
and state$
import React, { useState } from "react";
import ReactDOM from "react-dom";
import { useEventCallback } from "rxjs-hooks";
import { map, withLatestFrom, combineLatest } from "rxjs/operators";
import "./styles.css";
function App() {
const [count, setCount] = useState(0);
const [clickCallback, [description, x, y, prevDesc]] = useEventCallback(
(event$, state$, inputs$) =>
event$.pipe(
map(event => [event.target.innerHTML, event.clientX, event.clientY]),
combineLatest(inputs$),
withLatestFrom(state$),
map(([eventAndInput, state]) => {
const [[text, x, y], [count]] = eventAndInput;
const prevDescription = state[0];
return [text, x + count, y + count, prevDescription];
})
),
["nothing", 0, 0, "nothing"],
[count]
);
return (
<div className="App">
<h1>
click position: {x}, {y}
</h1>
<h1>"{description}" was clicked.</h1>
<h1>"{prevDesc}" was clicked previously.</h1>
<button onClick={clickCallback}>click me</button>
<button onClick={clickCallback}>click you</button>
<button onClick={clickCallback}>click him</button>
<div>
<p>
click buttons above, and then click this `+++` button, the position
numbers will grow.
</p>
<button onClick={() => setCount(count + 1)}>+++</button>
</div>
</div>
);
}
const rootElement = document.getElementById("root");
ReactDOM.render(<App />, rootElement);
Example of combining callback observables coming from separate elements - animation with start/stop button and rate controllable via slider
const Animation = ({ frame }) => {
const frames = "|/-\\|/-\\|".split("");
return (
<div>
<p>{frames[frame % frames.length]}</p>
</div>
);
};
const App = () => {
const defaultRate = 5;
const [running, setRunning] = useState(false);
const [onEvent, frame] = useEventCallback(events$ => {
const running$ = events$.pipe(
filter(e => e.type === "click"),
scan(running => !running, running),
startWith(running),
tap(setRunning)
);
return events$.pipe(
filter(e => e.type === "change"),
map(e => parseInt(e.target.value, 10)),
startWith(defaultRate),
switchMap(i => timer(200, 1000 / i)),
withLatestFrom(running$),
filter(([_, running]) => running),
scan(frame => frame + 1, 0)
);
});
return (
<div className="App">
<button onClick={onEvent}>{running ? "Stop" : "Start"}</button>
<input
type="range"
onChange={onEvent}
defaultValue={defaultRate}
min="1"
max="10"
></input>
<Animation frame={frame} />
</div>
);
};
If you are using React 18 + StrictMode
, rxjs-hooks
will not work properly. Because in React 18, StrictMode
will force unmount hooks to trigger twice, which will result in unexpected behaviours.
FAQs
React hooks for RxJS
The npm package rxjs-hooks receives a total of 1,848 weekly downloads. As such, rxjs-hooks popularity was classified as popular.
We found that rxjs-hooks demonstrated a not healthy version release cadence and project activity because the last version was released a year ago. It has 1 open source maintainer collaborating on the project.
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