How to use event handler with inside a styled component - reactjs

Question

import styled from "styled-components";
import pic from "./assets/images/bg-sidebar-desktop.svg";
const App=()=> {
const [index, setIndex] = useState(0);
const navitems = [
{
step: "Step 1",
value: "Your info",
},
{
step: "Step 2",
value: "Select plan",
},
{
step: "Step 3",
value: "Add-ons",
},
{
step: "Step 4",
value: "Summary",
},
];
return (
<Container>
<Navbar imgUrl={pic}>
{navitems.map((item, key) => {
return (
<>
<Index onClick={(key)=>setIndex(key)}>{key + 1}</Index>
<Heading>{item.step}</Heading>
<Content>{item.value}</Content>
</>
);
})}
</Navbar>
</Container>
);
}
const Container = styled.div`
height: 70.5vh;
width: 55vw;
margin: auto;
margin-top: calc(100vh / 7);
border-radius: 1em;
background-color: white;
overflow: hidden;
font-size: .9em;
`;
const Navbar = styled.div`
border: 1px solid black;
background-image: url(${(props) => props.imgUrl});
background-repeat: no-repeat;
background-position: 100% 100%;
height: 66.7vh;
width: 15.5vw;
border-radius: 1em;
margin-top: calc((3.6vh) / 2);
margin-left: 0.8em;
color: #ffffff;
text-transform: uppercase;
`;
const Heading = styled.div`
// border: 1px solid red;
color: hsl(231, 11%, 63%);
text-indent: 5.5em;
letter-spacing: .005em;
font-size: .9em;
`;
const Content = styled.div`
// border: 1px solid white;
text-indent: 5em;
letter-spacing: .1em;
font-weight: bolder;
`;
const Index = styled.span`
border: 1px solid white;
display: inline-block;
border-radius: 50%;
height: 2em;
width: 2em;
text-align: center;
padding-top: 0.3em;
box-sizing: border-box;
position: relative;
top: 7%;
left: 10%;
`;
export default App;
NOTE: There is an Index component and a useState variable whose name is also index. Don't get confused.
I want that everytime I click on the Index component the index useState variable gets updated to that particular key value .The above code applies the inline event handler to Index component but index state variable is not changed correctly on clicking that.On console logging the index a string gets output .Here's the string
"SyntheticBaseEvent {_reactName: 'onClick', _targetInst: null, type: 'click', nativeEvent: PointerEvent, target: span.sc-eDvSVe.iTaECf, …}"

Answer 1

Do this:
<Index onClick={() => setIndex(key)}>{key + 1}</Index>
Explaination:
// Normal syntax for onClick:
onClick = {(event) => someFunc()}
// Your Code
// here you pass key as an argument so key here means click event
// so what you give setIndex is the click event and not the key
onClick = {(key) => setIndex(key)}

Answer 2

In your case "key" is event, which returns from the button:
onClick={(key)=>setIndex(key)
just remove then "key" from params of func, then key will be take from array index:
<Navbar imgUrl={pic}>
{navitems.map((item, index) => {
return (
<>
<Index onClick={()=>setIndex(index)}>{index + 1}</Index>
<Heading>{item.step}</Heading>
<Content>{item.value}</Content>
</>
);
})}
</Navbar>