on click i want to generate alert in react js method - reactjs

Question

This is my code:
generateAlert = () => {
alert('hi');
}
return <Tile
click={(index)=>{this.generateAlert}}
title={tile.title}
value={tile.value}
key={tile.id}
/>
This is the error I'm getting:
Expected an assignment or function call and instead saw an expression no-unused-expressions
Search for the keywords to learn more about each error.

Answer 1

First, I do wonder if in your Component you have an array of Tile data, and you want to render a Tile for each entry of the array (I thought so because you added the key prop to Tile).
Anyways, I made an example similar to what you want to achieve, and it's working. Look at this:
const Tile = (props) => {
return (
<div className="Tile">
<h3>{props.title}</h3>
<div onClick={props.click}>
{props.value}
</div>
</div>
);
}
class App extends React.Component {
constructor(props) {
super(props);
}
generateAlert = () => {
alert("Hi");
}
render() {
return (
<Tile
click={this.generateAlert}
title={"This isa a Title"}
value={"This is the value"} />
);
}
}
ReactDOM.render(<App />, document.getElementById('root'));
#import url(https://fonts.googleapis.com/css?family=Montserrat);
body {
font-family: 'Montserrat', sans-serif;
}
<script src="https://cdnjs.cloudflare.com/ajax/libs/react/16.6.3/umd/react.production.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/react-dom/16.6.3/umd/react-dom.production.min.js"></script>
<div id='root'></div>
Now, I may help you in a deeper way if you would post the code of the Component that wants to render Tile; maybe, there are some error in that.

Answer 2

Hei!
If it's a function invocation inside your component's onClick function, you need to add () after this.generateAlert in your component
So it's gonna be like:
return <Tile
click={(index)=>{this.generateAlert()}}
title={tile.title}
value={tile.value}
key={tile.id}
/>
Otherwise, you can use your function as a onClick callback per se.
In that case you need to have it like this:
return <Tile
onClick={this.generateAlert}
title={tile.title}
value={tile.value}
key={tile.id}
/>
Cheers!

Answer 3

I will do in this way:
Q: why I export Tile to new component?
A: As each component should be as short as possible. There is a many advantages to doing in this way
like: "easy to find bugs (testing)".
import React, { Component } from "react";
import Tile from "./Tile";
import "./App.css";
class App extends Component {
constructor(props) {
super(props);
this.generateAlert = this.generateAlert.bind(this);
}
generateAlert = () => {
alert("Hi");
};
render() {
return (
<Tile
click={this.generateAlert}
title={"This isa a Title"}
value={"This is the value"}
/>
);
}
}
export default App;
and file Tile.js:
import React, { Component } from "react";
export default class Tile extends Component {
constructor(props) {
super(props);
}
render() {
return (
<div>
<button onClick={this.props.click}>click me</button>
<p>{this.props.title}</p>
<p>{this.props.value}</p>
</div>
);
}
}
This file Tile.js are ready for future addons but if you want to use only like it is now I would recommend to change into stateless component:
import React from "react";
const Tile = props => {
return (
<div>
<button onClick={props.click}>click me</button>
<p>{props.title}</p>
<p>{props.value}</p>
</div>
);
};
export default Tile;