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import { useState, useEffect } from 'react';
// Usage
function App() {
// Call our hook for each key that we'd like to monitor
const happyPress = useKeyPress('h');
const sadPress = useKeyPress('s');
const robotPress = useKeyPress('r');
const foxPress = useKeyPress('f');
return (
<div>
<div>h, s, r, f</div>
<div>
{happyPress && '😊'}
{sadPress && '😢'}
{robotPress && '🤖'}
{foxPress && '🦊'}
</div>
</div>
);
}
// Hook
function useKeyPress(targetKey) {
// State for keeping track of whether key is pressed
const [keyPressed, setKeyPressed] = useState(false);
// If pressed key is our target key then set to true
function downHandler({ key }) {
if (key === targetKey) {
setKeyPressed(true);
}
}
// If released key is our target key then set to false
const upHandler = ({ key }) => {
if (key === targetKey) {
setKeyPressed(false);
}
};
// Add event listeners
useEffect(() => {
window.addEventListener('keydown', downHandler);
window.addEventListener('keyup', upHandler);
// Remove event listeners on cleanup
return () => {
window.removeEventListener('keydown', downHandler);
window.removeEventListener('keyup', upHandler);
};
}, []); // Empty array ensures that effect is only run on mount and unmount
return keyPressed;
}
@hieund20
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hieund20 commented Feb 15, 2022

Codesanbox is not working

@Suryakaran1234
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Suryakaran1234 commented Apr 11, 2022

Hey, can someone help me out. I want to implement traversal through inputs (which are basically in table cells in a Table) using Arrow Keys (Up, Down, Left and Right). I am struggling to find a solution to do this. I have searched through Google But All the Solutions I have found are done using JQuery. My Goal is to Tackle this problem in React. I have tried this all the hooks present here. But none worked out for me. Maybe, I couldn't get it's logic because I am still a beginner.

@felipe-dap
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felipe-dap commented Apr 11, 2022

@Suryakaran1234
Cool. This seems like a nice challenge.
What I would try is something like this:

  1. Define a matrix-like identification with two integers. Maybe you already have it. I mean something like this:
 let table = [
    {row: 1, column: 1, content: "excel like cell 1A"},
    {row: 1, column: 2, content: "excel like cell 1B"},
    {row: 1, column: 3, content: "excel like cell 1C"},
    {row: 2, column: 1, content: "excel like cell 2A"},
    {row: 2, column: 2, content: "excel like cell 2B"},
    {row: 2, column: 3, content: "excel like cell 2C"},
] // and so on
  1. You may have a variable that gives what is your current active cell.
let active = [1, 3] //row and column, so it would point to 1C as active. 
  1. Define a few functions like so:
function moveDown(active)
    let [row, column] = active  //destructure array to have access to row and column
    // you will need some error boundaries if your table has a limit on the number of cells, say 50 rows, for example.
    if (row === 50) {
        return active //does nothing because there is not a cell below it to go to
    }
    return [row + 1, column]

function moveUp(active)
    let [row, column] = active  //destructure array to have access to row and column
    if (row === 1) {
        return active //does nothing because there is not a cell above it
    }
    return [row - 1, column]

function moveLeft(active)
    let [row, column] = active  //destructure array to have access to row and column
    if (column === 1) {
        return active //does nothing because there is not a cell to the left
    }
    return [row, column - 1]

function moveRight(active)
    let [row, column] = active  //destructure array to have access to row and column
    if (column === 50) {
        return active //does nothing beacuse column 50 is our table limit.
    }
    return [row, column + 1]
  1. Pack these functions into an object to abstract it. We know that keyCodes for arrows are:

37 --> left
38 --> up
39 --> right
40 --> down
So our hook function needs to detect a keypress, check if the keyCode is any of these values from 37 to 40 and call the event.

let actions = {
    37: moveLeft,
    38: moveUp,  
    39: moveRight,
    40: moveDown,
}

function useTraversalThroughInputs(initial) {
  const [active, setActive] = useState(initial) //active is our default value, the initial selected cell

  // keyboard key has been pressed
  function downHandler(e) {  
      if ([37, 38, 39, 40].includes(e.keyCode)) {
          let action = actions[e.keyCode] // this gives us the handler. say.. e.keyCode is 39, it returns moveLeft
          let newActiveCell = action(active) // receives the [1,1] and returns [1,2]
          setActive(newActiveCell) // active cell is now [1,2] and our hook returns it to our functional component
      }
  }

  // Add event listeners
  useEffect(() => {
    window.addEventListener('keydown', downHandler);
    // Remove event listeners on cleanup
    return () => {
      window.removeEventListener('keydown', downHandler);
    };
    }, []); // Empty array ensures that effect is only run on mount and unmount
    return active
}

Now our hook gives us the current cell position. We could go further and incorporate into the hook the ability to select the element and use input.focus() to make it active. But I will keep concerns separate here for clarity.

function Table() {
   let current = useTraversalThroughInputs(initial) // where initial is the default active cell 

  useEffect(() => {
     // select the input element. depends on the structure of your table.
     let element = document.getElementBy... 
     element.focus()
    // useEffect you be triggered every time active has been changed, and will change focus to your new active cell.
  }, [active])
)

return (
   /// your table content with some sort of identification for selecting cells based on [row, column].
)


@Suryakaran1234
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Suryakaran1234 commented Apr 11, 2022

Thank you so Much for this, I will be implementing it right away and let you know if I face any issues😊.

@Suryakaran1234
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Suryakaran1234 commented Apr 11, 2022

@felipe-dap
Hey, I tried your solution but it's a little more complicated for me and my code just became more complex. Can you help me out with this, I am struggling pretty hard to implement this.

This is My Component

Here is my component (I am using Material UI v5) 👇🏻

`import * as PropTypes from 'prop-types';
import styled from '@emotion/styled';
import { css } from '@emotion/react';
import { Grid } from '@mui/material';
import useTraversalThroughInputs from './useTraversalThroughInputs';
import { useEffect } from 'react';

const styles = csswidth: 100%; padding: 0 10px; border: 1px solid black; font-size: 14px; font-weight: bold; margin: 5px 0 0 0; height: 25px; border-radius: 2px;;

const titleStyles = csswidth: 20%; height: 5vh; text-align: center; padding: 5px 25px; font-style: italic; font-size: 1rem; color: #fff;;

const StyledOpen = styled.td${titleStyles}; background-color: #ce4848;;

const StyledJodi = styled.td${titleStyles}; color: #000; background-color: #37e180;;

const StyledClose = styled.td${titleStyles}; background-color: #000;;

const StyledInput = styled.input${styles};

const StyledOpenInput = styled.inputbackground-color: #ce4848; ${styles};

const StyledCloseInput = styled.inputcolor: #fff; background-color: #000; ${styles};

function Jodi({ jodiArr = [] }) {
// eslint-disable-next-line prefer-const
let active = [1, 1]; // row and column, so it would point to 1C as active.

const current = useTraversalThroughInputs(active);
const jodi = [...jodiArr];
const row = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12];
const column = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12];

useEffect(() => {
    // select the input element. depends on the structure of your table.
    const tableBody = document.querySelector('#table-body ');
    tableBody.focus();
    // useEffect you be triggered every time active has been changed, and will change focus to your new active cell.
}, [active]);

const openClose = jodi.slice(0, 10);

console.log(jodi);

return (
    <>
        <Grid container spacing={1} component="table" direction="column" justifyContent="space-between">
            <thead>
                <Grid item component="tr" sx={{ display: 'flex', justifyContent: 'space-between' }}>
                    <StyledOpen>Open</StyledOpen>
                    <StyledJodi>Jodi</StyledJodi>
                    <StyledClose>Close</StyledClose>
                </Grid>
            </thead>
            <tbody id="table-body">
                {openClose.map((open, index) => {
                    const jodis = jodi.splice(0, 10);
                    // eslint-disable-next-line prefer-const
                    let indexJodi = index * 10;

                    return (
                        <tr key={open} id={row[index]}>
                            <Grid item xs={1} md={1} xl={1} component="td">
                                <label htmlFor={`OPEN_${open}`}>{open}</label>
                                <StyledOpenInput type="text" id={column[index]} name={`OPEN_${open}`} />
                            </Grid>
                            {jodis.map((jodi, indexJ) => (
                                <Grid item key={indexJodi + indexJ} xs={1} md={1} xl={1} component="td">
                                    <label htmlFor={`Jodi_${jodi}`}>{jodi}</label>
                                    <StyledInput type="text" id={column[index]} name={`Jodi_${jodi}`} />
                                </Grid>
                            ))}
                            <Grid item key={open + 2} xs={1} md={1} xl={1} component="td">
                                <label htmlFor={`CLOSE_${open}`}>{open}</label>
                                <StyledCloseInput type="text" id={column[index]} name={`CLOSE_${open}`} />
                            </Grid>
                        </tr>
                    );
                })}
            </tbody>
        </Grid>
    </>
);

}

Jodi.propTypes = {
jodiArr: PropTypes.array
};

export default Jodi;
`

Here is My Array that I am passing to this component👇🏻

`const jodiArr = [
"00", "01", "02", "03", "04", "05", "06", "07", "08", "09",
"10", "11", "12", "13", "14", "15", "16", "17", "18", "19",
"20", "21", "22", "23", "24", "25", "26", "27", "28", "29",
"30", "31", "32", "33", "34", "35", "36", "37", "38", "39",
"40", "41", "42", "43", "44", "45", "46", "47", "48", "49",
"50", "51", "52", "53", "54", "55", "56", "57", "58", "59",
"60", "61", "62", "63", "64", "65", "66", "67", "68", "69",
"70", "71", "72", "73", "74", "75", "76", "77", "78", "79",
"80", "81", "82", "83", "84", "85", "86", "87", "88", "89",
"90", "91", "92", "93", "94", "95", "96", "97", "98", "99"];

export default jodiArr;
`

@felipe-dap
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felipe-dap commented Apr 12, 2022

@Suryakaran1234
Sure I can help you out on this. =)
Do you mind if I make a few refactorings along the way? Mostly for organization pourposes...
This is getting way off topic, so I made a repo in order for not cluttering this thread anymore.
Probably tomorrow there should be a demo on there. Find me there.
https://github.com/felipe-dap/useTraversalThroughInputs
and we can chat at
felipe-dap/useTraversalThroughInputs#1
Cheers.

@Suryakaran1234
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Suryakaran1234 commented Apr 13, 2022

@felipe-dap
Yeah of course go ahead, it will be helpful for me if you do refactorings, I will get to learn more.

@eli7gn
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eli7gn commented Jul 25, 2022

function testUseKeyPress() {
 const onPressSingle = () => {
    console.log('onPressSingle!')
  }
  const onPressMulti = () => {
    console.log('onPressMulti!')
  }

  useKeyPress('a', onPressSingle)
  useKeyPress('shift h', onPressMulti)
}
onKeyPressed

Thanks @jeremytenjo

@Chandraprakash-Darji
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Chandraprakash-Darji commented Nov 11, 2022

For folks attempting to capture Meta key pressed in combination with other keys (Command+k e.g. on Macs), be warned that keyup events do not fire when the Meta key is still pressed. That means that this hook cannot be used reliably to detect when keys are unpressed. Read issue #3 here: https://web.archive.org/web/20160304022453/http://bitspushedaround.com/on-a-few-things-you-may-not-know-about-the-hellish-command-key-and-javascript-events/

To work around this, I do not rely on keyup events at all but instead "unpress" automatically after a second. It's a bit hacky but serves my use case quite well (Command+k):

export function useKeyPress(targetKey: string) {
  // State for keeping track of whether key is pressed
  const [keyPressed, setKeyPressed] = useState<boolean>(false);
  // Add event listeners
  useEffect(() => {
    // If pressed key is our target key then set to true
    function downHandler({ key }: any) {
      if (!keyPressed && key === targetKey) {
        setKeyPressed(true);
        // rather than rely on keyup to unpress, use a timeout to workaround the fact that
        // keyup events are unreliable when the meta key is down. See Issue #3:
        // http://web.archive.org/web/20160304022453/http://bitspushedaround.com/on-a-few-things-you-may-not-know-about-the-hellish-command-key-and-javascript-events/
        setTimeout(() => {
          setKeyPressed(false);
        }, 1000);
      }
    }

    window.addEventListener("keydown", downHandler);
    // Remove event listeners on cleanup
    return () => {
      window.removeEventListener("keydown", downHandler);
    };
  }, []); // Empty array ensures that effect is only run on mount and unmount
  return keyPressed;
}

And if anyone is interested, here's my tiny useKeyCombo extension that can be used like const isComboPress = useKeyCombo("Meta+k"); to capture Command+k:

export const useKeyCombo = (keyCombo: string) => {
  const keys = keyCombo.split("+");
  const keyPresses = keys.map((key) => useKeyPress(key));

  return keyPresses.every(keyPressed => keyPressed === true);
};

Lastly, I almost always just want to trigger some logic when these key conditions are met, so I made a wrapper hook that does that for me and allows for usage like this: useOnKeyPressed("Meta+k", () => setIsQuickSearchOpen(true)); :

export const useOnKeyPressed = (keyCombo: string, onKeyPressed: () => void) => {
  const isKeyComboPressed = useKeyCombo(keyCombo);

  useEffect(() => {
    if (isKeyComboPressed) {
      onKeyPressed();
    }
  }, [isKeyComboPressed]);
};

have encountourred any problem while using this?

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