Use event handler to change button appearance - reactjs

Question

I would like to build out my functional component BoldButton in which when the user clicks either the lowercase a or uppercase A, the text of the button is changed to bold. Below is my work in progress.
import React, { useEffect, useState } from 'react';
const BoldButon = () => {
const [color, setColor] = useState("black")
useEffect(() => {
})
const changeColor = () => {
setColor("black")
}
return (
<div>
<button text={{style:color}} onClick={changeColor}>
A
</button>
<button text={{style:color}} onClick={changeColor}>
a
</button>
</div>
)
}
export default BoldButon;
This was one problem I had when doing a mock technical interview so I would like to know how to solve it when using a functional component. **Not sure if I need to utilize useEffect in order to solve this.

Answer 1

Currently, there are a few problems with syntax to address:
text={{style:color}} not sure what this is supposed to do: text is not a standard or custom prop that you have set anywhere on the button component. Also, say you were to change the color of the button's text (which you could do with style={{color}} then you would be able to change it from let's say black to gray or black to yellow for different emphasis, but you seemed to say that you wanted different font-weight (bold vs not bold) is controlled by the CSS property font-weight (and that can be set in HTML or JSX through the style property that all elements can have.
if you have nothing in useEffect probably you can/should get rid of it. useEffect is useful for if the state of something changes and you need a side effect you can put it there (or it can be used as a strange componentDidMount which will only run after all parents have had their useEffect run.
For something like this it might be better to use a class and then you can set a number of style properties with a single string: like is-emphasized is a commonly used class that can change the font-weight to 600 and the color to black from a dark gray (if necessary).
You probably want individual states for each individual button (as you want each button to be bold if it was clicked: it seems based on your question).
.is-emphasized {
font-weight: 600;
color: #000;
}
But if not the simplest fastest way to approach this is:
<button
style={{fontWeight: bold ? 'bold' : 'normal'}}
onClick={changeWeight}
>
A
</button>
<button
style={{fontWeight: !bold ? 'bold' : 'normal'}}
onClick={changeWeight}
>
a
</button>
function BoldButon() {
const [capitalABold, setCapitalABold] = React.useState(false)
const [aBold, setaBold] = React.useState(false);
const changeColor = () => {
setColor("black")
}
return (
<div>
<button
className={capitalABold ? 'is-emphasized' : ''}
onClick={() => setCapitalABold(!capitalABold)}
>
A
</button>
<button
className={aBold ? 'is-emphasized' : ''}
onClick={() => setaBold(!aBold)}
>
a
</button>
</div>
)
}
ReactDOM.render(<BoldButon/>, document.getElementById("root"));
* {
color: #333;
font-size: 14px;
}
.is-emphasized {
color: #000;
font-weight: 600;
}
<script src="https://cdnjs.cloudflare.com/ajax/libs/react/17.0.1/umd/react.production.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/react-dom/17.0.1/umd/react-dom.production.min.js"></script>
<div id="root"></div>

Answer 2

You don't need useEffect for this kind of functionality, you can utilize the useState hook to manage the variable that determines if the user has clicked on the button. Also, you can use the useMemo hook to keep the style object which returns either bold or normal. Please note that the toggleBold toggles the font weight so if a user is clicking multiple times it will switch between the bold and normal.
import React, { useState, useMemo } from 'react';
const BoldButon = () => {
const [boldA, setBoldA] = useState(false)
const [boldB, setBoldB] = useState(false)
const toggleBold = (buttonType) => () => {
if(buttonType === 'firstButton') {
setBoldA(prevState => !prevState)
} else {
setBoldB(prevState => !prevState)
}
}
const buttonStyleA = useMemo(() => {
return {fontWeight: boldA ? 'bold' : 'normal'}
}, [boldA])
const buttonStyleB = useMemo(() => {
return {fontWeight: boldB ? 'bold' : 'normal'}
}, [boldB])
return (
<div>
<button style={buttonStyleA} onClick={toggleBold('firstButton')}>
A
</button>
<button style={buttonStyleB} onClick={toggleBold('secondButton')}>
B
</button>
</div>
)
}
export default BoldButon;