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Cannot get synced state in React INK when using "useStdin" hook with rawMode

I'm using ink package, and I'm building the following component:
MultiSelect.tsx file:
import React, { useEffect, useState } from 'react';
import { useStdin } from 'ink';
import type { ISelectItem, ISelectItemSelection } from './interfaces/select-item';
import { ARROW_DOWN, ARROW_UP, ENTER, SPACE } from './constants/input';
import MultiSelectView from './MultiSelect.view';
interface IProps {
readonly items: ISelectItem[];
readonly onSubmit: (selectedItems: string[]) => void;
}
const MultiSelect: React.FC<IProps> = (props: React.PropsWithChildren<IProps>) => {
const { stdin, setRawMode } = useStdin();
const [itemsSelectionState, setItemsSelectionState] = useState<ISelectItemSelection[]>(
props.items.map((item, index) => ({ ...item, selected: false, isHighlighted: index === 0 })),
);
const stdinInputHandler = (data: unknown) => {
const rawData = String(data);
if (rawData === ARROW_DOWN) {
setItemsSelectionState((prev) => {
const highlightedIndex = prev.findIndex((item) => item.isHighlighted);
if (highlightedIndex === -1) {
return prev;
}
const clonedPrev = structuredClone(prev);
clonedPrev[highlightedIndex]!.isHighlighted = false;
if (highlightedIndex === prev.length - 1) {
clonedPrev[0]!.isHighlighted = true;
} else {
clonedPrev[highlightedIndex + 1]!.isHighlighted = true;
}
return clonedPrev;
});
}
if (rawData === ARROW_UP) {
setItemsSelectionState((prev) => {
const highlightedIndex = prev.findIndex((item) => item.isHighlighted);
if (highlightedIndex === -1) {
return prev;
}
const clonedPrev = structuredClone(prev);
clonedPrev[highlightedIndex]!.isHighlighted = false;
if (highlightedIndex === 0) {
clonedPrev[prev.length - 1]!.isHighlighted = true;
} else {
clonedPrev[highlightedIndex - 1]!.isHighlighted = true;
}
return clonedPrev;
});
}
if (rawData === SPACE) {
setItemsSelectionState((prev) => {
const highlightedIndex = prev.findIndex((item) => item.isHighlighted);
if (highlightedIndex === -1) {
return prev;
}
const clonedPrev = structuredClone(prev);
clonedPrev[highlightedIndex]!.selected = !prev[highlightedIndex]!.selected;
return clonedPrev;
});
}
if (rawData === ENTER) {
const selectedItemsValues = itemsSelectionState
.filter((item) => item.selected)
.map((item) => item.value);
props.onSubmit(selectedItemsValues);
}
};
useEffect(() => {
setRawMode(true);
stdin?.on('data', stdinInputHandler);
return () => {
stdin?.removeListener('data', stdinInputHandler);
setRawMode(false);
};
}, []);
return <MultiSelectView itemsSelection={itemsSelectionState} />;
};
export default MultiSelect;
MultiSelect.view.tsx file:
import { Box, Text } from 'ink';
import React from 'react';
import type { ISelectItemSelection } from './interfaces/select-item';
interface IProps {
readonly itemsSelection: ISelectItemSelection[];
}
const MultiSelectView: React.FC<IProps> = (props: React.PropsWithChildren<IProps>) => {
return (
<Box display="flex" flexDirection="column">
{props.itemsSelection.map((item) => (
<Box key={item.value} display="flex" flexDirection="row">
<Text color="blue">{item.isHighlighted ? '❯' : ' '}</Text>
<Text color="magenta">
{item.selected ? '◉' : '◯'}
</Text>
<Text color="white" bold={item.selected}>
{item.label}
</Text>
</Box>
))}
</Box>
);
};
export default MultiSelectView;
Then, when I use this component in my code:
const onSubmitItems = (items: string[]) => {
console.log(items);
};
render(<MultiSelect items={items} onSubmit={onSubmitItems} />);
the render function is imported from ink and items is something like [{value: 'x', label: 'x'}, {value:'y', label:'y'}]
When I hit the enter key, Then onSubmitItems is triggered, but it outputs empty list, although I did select some items...
For example, in this output:
I picked 3 items, but output is still empty list. And it does seem like the state changes, so why I don't get the updated state?

You can resolve the issue by using useCallback:
const stdinInputHandler = useCallback((data: Buffer) => {
const rawData = String(data);
if (rawData === ARROW_DOWN) {
setItemsSelectionState((prev) => {
const highlightedIndex = prev.findIndex((item) => item.isHighlighted);
if (highlightedIndex === -1) {
return prev;
}
const clonedPrev = structuredClone(prev);
clonedPrev[highlightedIndex]!.isHighlighted = false;
if (highlightedIndex === prev.length - 1) {
clonedPrev[0]!.isHighlighted = true;
} else {
clonedPrev[highlightedIndex + 1]!.isHighlighted = true;
}
return clonedPrev;
});
}
if (rawData === ARROW_UP) {
setItemsSelectionState((prev) => {
const highlightedIndex = prev.findIndex((item) => item.isHighlighted);
if (highlightedIndex === -1) {
return prev;
}
const clonedPrev = structuredClone(prev);
clonedPrev[highlightedIndex]!.isHighlighted = false;
if (highlightedIndex === 0) {
clonedPrev[prev.length - 1]!.isHighlighted = true;
} else {
clonedPrev[highlightedIndex - 1]!.isHighlighted = true;
}
return clonedPrev;
});
}
if (rawData === SPACE) {
setItemsSelectionState((prev) => {
const highlightedIndex = prev.findIndex((item) => item.isHighlighted);
if (highlightedIndex === -1) {
return prev;
}
const clonedPrev = structuredClone(prev);
clonedPrev[highlightedIndex]!.selected = !prev[highlightedIndex]!.selected;
return clonedPrev;
});
}
if (rawData === ENTER) {
const selectedItemsValues = itemsSelectionState
.filter((item) => item.selected)
.map((item) => item.value);
props.onSubmit(selectedItemsValues);
}
}, [itemsSelectionState]);
Then, in your useEffect:
useEffect(() => {
setRawMode(true);
stdin?.on('data', stdinInputHandler);
return () => {
stdin?.removeListener('data', stdinInputHandler);
setRawMode(false);
};
}, [stdinInputHandler]);
now useEffect will re-register the input handler with new functions locals up-to-date with the state

Converting class component to functional component TypeError: users.filter is not a function

Making a employee directory and I'm trying to convert class component into functional component. The nav, search, and table will render but the call to the api isn't working. Getting a
TypeError: users.filter is not a function Here is the class component that works and the in progress functional component. I can't figure out what is different.
import React, { Component } from "react";
import DataTable from "./DataTable";
import Nav from "./Nav";
import API from "../utils/API";
import "../styles/DataArea.css";
export default class DataArea extends Component {
state = {
users: [{}],
order: "descend",
filteredUsers: [{}]
}
headings = [
{ name: "Image", width: "10%" },
{ name: "Name", width: "10%" },
{ name: "Phone", width: "20%" },
{ name: "Email", width: "20%" },
{ name: "DOB", width: "10%" }
]
handleSort = heading => {
if (this.state.order === "descend") {
this.setState({
order: "ascend"
})
} else {
this.setState({
order: "descend"
})
}
const compareFnc = (a, b) => {
if (this.state.order === "ascend") {
// account for missing values
if (a[heading] === undefined) {
return 1;
} else if (b[heading] === undefined) {
return -1;
}
// numerically
else if (heading === "name") {
return a[heading].first.localeCompare(b[heading].first);
} else {
return a[heading] - b[heading];
}
} else {
// account for missing values
if (a[heading] === undefined) {
return 1;
} else if (b[heading] === undefined) {
return -1;
}
// numerically
else if (heading === "name") {
return b[heading].first.localeCompare(a[heading].first);
} else {
return b[heading] - a[heading];
}
}
}
const sortedUsers = this.state.filteredUsers.sort(compareFnc);
this.setState({ filteredUsers: sortedUsers });
}
handleSearchChange = event => {
console.log(event.target.value);
const filter = event.target.value;
const filteredList = this.state.users.filter(item => {
// merge data together, then see if user input is anywhere inside
let values = Object.values(item)
.join("")
.toLowerCase();
return values.indexOf(filter.toLowerCase()) !== -1;
});
this.setState({ filteredUsers: filteredList });
}
componentDidMount() {
API.getUsers().then(results => {
this.setState({
users: results.data.results,
filteredUsers: results.data.results
});
});
}
render() {
return (
<>
<Nav handleSearchChange={this.handleSearchChange} />
<div className="data-area">
<DataTable
headings={this.headings}
users={this.state.filteredUsers}
handleSort={this.handleSort}
/>
</div>
</>
);
}
}
import React, { useState, useEffect } from "react";
import DataTable from "./DataTable";
import Nav from "./Nav";
import API from "../utils/API";
import "../styles/DataArea.css";
const DataArea = () => {
const [users, setUsers] = useState([{}]);
const [order, setOrder] = useState("descend");
const [filteredUsers, setFilteredUsers] = useState([{}]);
const headings = [
{ name: "Image", width: "10%" },
{ name: "Name", width: "10%" },
{ name: "Phone", width: "20%" },
{ name: "Email", width: "20%" },
{ name: "DOB", width: "10%" },
];
const handleSort = (heading) => {
if (order === "descend") {
setOrder((order = "ascend"));
} else {
setOrder((order = "descend"));
}
const compareFnc = (a, b) => {
if (order === "ascend") {
// account for missing values
if (a[heading] === undefined) {
return 1;
} else if (b[heading] === undefined) {
return -1;
}
// numerically
else if (heading === "name") {
return a[heading].first.localeCompare(b[heading].first);
} else {
return a[heading] - b[heading];
}
} else {
// account for missing values
if (a[heading] === undefined) {
return 1;
} else if (b[heading] === undefined) {
return -1;
}
// numerically
else if (heading === "name") {
return b[heading].first.localeCompare(a[heading].first);
} else {
return b[heading] - a[heading];
}
}
};
const sortedUsers = filteredUsers.sort(compareFnc);
setFilteredUsers({ filteredUsers: sortedUsers });
};
let handleSearchChange = (event) => {
console.log(event.target.value);
const filtered = event.target.value;
const filteredList = users.filter((item) => {
// merge data together, then see if user input is anywhere inside
let values = Object.values(item).join("").toLowerCase();
return values.indexOf(filtered.toLowerCase()) !== -1;
});
setFilteredUsers((filteredUsers = filteredList));
};
useEffect(() => {
API.getUsers().then((results) => {
setUsers({
users: results.data.results,
filteredUsers: results.data.results,
});
});
}, []);
return (
<>
<Nav handleSearchChange={handleSearchChange} />
<div className="data-area">
<DataTable
headings={headings}
users={filteredUsers}
handleSort={handleSort}
/>
</div>
</>
);
};
export default DataArea;

The issue is in your useEffect hook where you shoehorn both users and filteredUsers into your users state.
useEffect(() => {
API.getUsers().then((results) => {
setUsers({
users: results.data.results,
filteredUsers: results.data.results,
});
});
}, []);
It should be
useEffect(() => {
API.getUsers().then((results) => {
setUsers(results.data.results);
setFilteredUsers(results.data.results),
});
}, []);
You want to populate both the users state, and separately the filteredUsers state.
An issue with setting the sorting order, you are mutating the order state:
if (order === "descend") {
setOrder((order = "ascend")); // <-- mutates
} else {
setOrder((order = "descend")); // <-- mutates
}
You can simply toggle between the two:
setOrder(order => order === 'ascend' ? 'descend' : 'ascend');
Another issue is at the end of your handleSort function:
const sortedUsers = filteredUsers.sort(compareFnc);
setFilteredUsers({ filteredUsers: sortedUsers });
This will nest the filteredUsers array, and also mutates the array in-place, it should probably use a functional state update to update from the previous state, use array.slice to make a copy, and then call sort.
setFilteredUsers(filteredUsers => filteredUsers.slice().sort(compareFnc));

I have a stopwatch in reactjs, how can I add each number into some sort of array to show each number?

I created a stopwatch using react. My stopwatch starts from 0 and stops at the press of the space button with componenDidMount and componentWillMount. My issue is, I can't seem to figure out how to create some sort of list with the numbers the stopwatch returns. I've created:
times = () => {
this.setState(previousState => ({
myArray: [...previousState.myArray, this.state.milliSecondsElapsed]
}));
};
and then in render() to print it.
<h1>{this.times}</h1>
What I'm trying to do is to create some sort of array that'll keep track of milliSecondsElapsed in my handleStart and handleStop method.
Here's what I have.
import React, {Component} from "react";
import Layout from '../components/MyLayout.js';
export default class Timer extends React.Component {
constructor(props) {
super(props);
this.state = {
milliSecondsElapsed: 0,
timerInProgress: false // state to detect whether timer has started
};
this.updateState = this.updateState.bind(this);
this.textInput = React.createRef();
}
componentDidMount() {
window.addEventListener("keypress", this.keyPress);
}
componentWillUnmount() {
window.removeEventListener("keypress", this.keyPress);
}
textInput = () => {
clearInterval(this.timer);
};
updateState(e) {
this.setState({})
this.setState({ milliSecondsElapsed: e.target.milliSecondsElapsed });
}
keyPress = (e) => {
if (e.keyCode === 32) {
// some logic to assess stop/start of timer
if (this.state.milliSecondsElapsed === 0) {
this.startBtn.click();
} else if (this.state.timerInProgress === false) {
this.startBtn.click();
} else {
this.stopBtn.click();
}
}
};
handleStart = () => {
if (this.state.timerInProgress === true) return;
this.setState({
milliSecondsElapsed: 0
});
this.timer = setInterval(() => {
this.setState(
{
milliSecondsElapsed: this.state.milliSecondsElapsed + 1,
timerInProgress: true
},
() => {
this.stopBtn.focus();
}
);
}, 10);
};
handleStop = () => {
this.setState(
{
timerInProgress: false
},
() => {
clearInterval(this.timer);
this.startBtn.focus();
}
);
};
times = () => {
this.setState(previousState => ({
myArray: [...previousState.myArray, this.state.milliSecondsElapsed]
}));
};
render() {
return (
<Layout>
<div className="index" align='center'>
<input
value={this.state.milliSecondsElapsed/100}
onChange={this.updateState}
ref={this.textInput}
readOnly={true}
/>
<button onClick={this.handleStart} ref={(ref) => (this.startBtn = ref)}>
START
</button>
<button onClick={this.handleStop} ref={(ref) => (this.stopBtn = ref)}>
STOP
</button>
<h1>{this.state.milliSecondsElapsed/100}</h1>
</div>
</Layout>
);
}
}

Issue
this.times is a function that only updates state, it doesn't return any renderable JSX.
times = () => {
this.setState((previousState) => ({
myArray: [...previousState.myArray, this.state.milliSecondsElapsed]
}));
};
Solution
Create a myArray state.
this.state = {
myArray: [], // <-- add initial empty array
milliSecondsElapsed: 0,
timerInProgress: false // state to detect whether timer has started
};
Move the state update logic from this.times to this.handleStop.
handleStop = () => {
this.setState(
(previousState) => ({
timerInProgress: false,
myArray: [
...previousState.myArray, // <-- shallow copy existing data
this.state.milliSecondsElapsed / 100 // <-- add new time
]
}),
() => {
clearInterval(this.timer);
this.startBtn.focus();
}
);
};
Render the array of elapsed times as a comma separated list.
<div>{this.state.myArray.join(", ")}</div>
Full code
class Timer extends React.Component {
constructor(props) {
super(props);
this.state = {
myArray: [],
milliSecondsElapsed: 0,
timerInProgress: false // state to detect whether timer has started
};
this.updateState = this.updateState.bind(this);
this.textInput = React.createRef();
}
componentDidMount() {
window.addEventListener("keypress", this.keyPress);
}
componentWillUnmount() {
window.removeEventListener("keypress", this.keyPress);
}
textInput = () => {
clearInterval(this.timer);
};
updateState(e) {
this.setState({ milliSecondsElapsed: e.target.milliSecondsElapsed });
}
keyPress = (e) => {
if (e.keyCode === 32) {
// some logic to assess stop/start of timer
if (this.state.milliSecondsElapsed === 0) {
this.startBtn.click();
} else if (this.state.timerInProgress === false) {
this.startBtn.click();
} else {
this.stopBtn.click();
}
}
};
handleStart = () => {
if (this.state.timerInProgress === true) return;
this.setState({
milliSecondsElapsed: 0
});
this.timer = setInterval(() => {
this.setState(
{
milliSecondsElapsed: this.state.milliSecondsElapsed + 1,
timerInProgress: true
},
() => {
this.stopBtn.focus();
}
);
}, 10);
};
handleStop = () => {
this.setState(
(previousState) => ({
timerInProgress: false,
myArray: [
...previousState.myArray,
this.state.milliSecondsElapsed / 100
]
}),
() => {
clearInterval(this.timer);
this.startBtn.focus();
}
);
};
render() {
return (
<div>
<div className="index" align="center">
<input
value={this.state.milliSecondsElapsed / 100}
onChange={this.updateState}
ref={this.textInput}
readOnly={true}
/>
<button
onClick={this.handleStart}
ref={(ref) => (this.startBtn = ref)}
>
START
</button>
<button onClick={this.handleStop} ref={(ref) => (this.stopBtn = ref)}>
STOP
</button>
<h1>{this.state.milliSecondsElapsed / 100}</h1>
</div>
<div>{this.state.myArray.join(", ")}</div>
</div>
);
}
}

how to use clearInteval let timer clear it self in ReactJS?

I am new to react, I am trying to write a react component, component has several features.
user can input a random number, then number will be displayed in the
page too.
implement a button with text value 'start', once click the button,
the number value displayed will reduce one every 1second and the
text value will become 'stop'.
continue click button, minus one will stop and text value of button
will become back to 'start'.
when number subtracted down to 0 will automatically stop itself.
I have implemented first three features. but I am not sure how do I start the last one. should I set another clearInteval? based on if statement when timer counts down 0?
code is here:
var myTimer;
class App extends Component {
constructor(props) {
super(props);
this.state = {
details: [{ id: 1, number: "" }],
type: false
};
this.handleClick = this.handleClick.bind(this);
}
changeNumber = (e, target) => {
this.setState({
details: this.state.details.map(detail => {
if (detail.id === target.id) {
detail.number = e.target.value;
}
return detail;
})
});
};
handleClick = () => {
this.setState(prevState => ({
type: !prevState.type
}));
if (this.state.type === false) {
myTimer = setInterval(
() =>
this.setState({
details: this.state.details.map(detail => {
if (detail.id) {
detail.number = parseInt(detail.number) - 1;
}
return detail;
})
}),
1000
);
}
if (this.state.type === true) {
clearInterval(myTimer);
}
};
render() {
return (
<div>
{this.state.details.map(detail => {
return (
<div key={detail.id}>
Number:{detail.number}
<input
type="number"
onChange={e => this.changeNumber(e, detail)}
value={detail.number}
/>
<input
type="button"
onClick={() => this.handleClick()}
value={this.state.type ? "stop" : "start"}
/>
</div>
);
})}
</div>
);
}
}
export default App;

just add
if (detail.number === 0) {
clearInterval(myTimer);
}
in
handleClick = () => {
this.setState(prevState => ({
type: !prevState.type
}));
if (this.state.type === false) {
myTimer = setInterval(
() =>
this.setState({
details: this.state.details.map(detail => {
if (detail.id) {
detail.number = parseInt(detail.number) - 1;
if (detail.number === 0) {
clearInterval(myTimer);
}
}
return detail;
})
}),
1000
);
}
if (this.state.type === true) {
clearInterval(myTimer);
}
};
Here You have this solution on Hooks :)
const Test2 = () => {
const [on, setOn] = useState(false)
const initialDetails = [{ id: 1, number: "" }]
const [details, setDetails] = useState(initialDetails)
const changeNumber = (e, target) => {
setDetails({ details: details.map(detail => { if (detail.id === target.id) { detail.number = e.target.value; } return detail; }) });
if (this.state.details.number === 0) { setOn(false) }
};
const handleClick = () => {
if (on === false) {myTimer = setInterval(() =>
setDetails({details: details.map(detail => {if (detail.id) {detail.number = parseInt(detail.number) - 1; if (detail.number === 0) {clearInterval(myTimer);} }
return detail;})}),1000);}
if (on === true) { clearInterval(myTimer); }
};
return (
<div>
{details.map(detail => {
return (
<div key={detail.id}>
Number:{detail.number}
<input
type="number"
onChange={e => changeNumber(e, detail)}
value={detail.number}
/>
<input
type="button"
onClick={() => handleClick()}
value={on ? "stop" : "start"}
/>
</div>
);
})}
</div>
)
}

Trying to set up form validation in my basic todo list app

I am trying to set up validations in my todo list app in react; however this doesn't seem to work. Even if the form is empty the process still goes through and I don't know where the problem is coming from. I am just following a tutorial online since I'm pretty new to this and don't know how to do it myself.
import React from "react";
import * as TodoActions from "../actions/TodoActions";
import TodoStore from "../stores/TodoStore";
import Todo from './Todo.js'
import './Todos.css'
const formValid = ({ formErrors, ...rest }) => {
let valid = true;
Object.values(formErrors).forEach(val => {
val.length > 0 && (valid = false);
});
Object.values(rest).forEach(val => {
val === null && (valid = false);
});
return valid;
};
export default class Todos extends React.Component {
constructor() {
super();
this.state = {
todos: TodoStore.getAll(),
loading: true,
formErrors: {
todo: ""
}
};
TodoActions.receiveTodos()
}
componentWillMount() {
TodoStore.addChangeListener(this.getTodos);
}
componentWillUnmount() {
TodoStore.removeChangeListener(this.getTodos);
}
componentDidUpdate() {
TodoActions.receiveTodos();
}
getTodos = () => {
this.setState({
todos: TodoStore.getAll(),
loading: false
});
}
deleteTodo = (id) => {
TodoActions.deleteTodo(id);
}
addItem = (e) => {
e.preventDefault();
TodoActions.createTodo(this._inputElement.value)
}
handleChange = e => {
e.preventDefault();
const { name, value } = e.target;
let formErrors = { ...this.state.formErrors };
switch (name) {
case "todo":
formErrors.todo =
value.length < 0 ? "Task cannot be empty" : "";
break;
default:
break;
}
this.setState({ formErrors, [name]: value }, () => console.log(this.state));
}
render() {
const { todos } = this.state;
const { formErrors } = this.state;
let TodoComponents;
if (this.state.loading) {
TodoComponents = <h1>Loading...</h1>;
} else if(todos.length) {
TodoComponents = todos.map((todo) => {
return (
<div key={todo.id} className="todo-list">
<Todo key={todo.id} name={todo.name}/>
<div className="todo-btn"><a type="button" onClick={() => this.deleteTodo(todo.id)} className="delete-btn"><i class="fas fa-trash-alt"></i></a></div>
</div>
)
});
} else {
TodoComponents = <p>No tasks to show :)</p>
}
return (
<div className="main-container">
<div className="small-container">
<h1 className="title">All Tasks</h1>
<ul>{TodoComponents}</ul>
<form onSubmit={this.addItem}>
<input ref={(a) => this._inputElement = a} placeholder="Enter Task" className="input-form {formErrors.todo.length < 0 ? 'error' : null}"/>
{formErrors.todo.length < 0 && (
<span className="errorMessage">{formErrors.firstName}</span>
)}
<button type="submit" className="input-btn">Add</button>
</form>
</div>
</div>
);
}
}