Caveat: This sounds like an X/Y problem, where the underlying problem (whatever it is) should be solved differently, so that you don't have to add a click handler to a DOM element created via dangerouslySetInnerHTML (ideally, so you don't have to create DOM elements via dangerouslySetInnerHTML at all). But answering the question you asked: (You've clarified the use case; solution #1 below applies and isn't poor practice.)
I don't think you can do that directly. Two solutions I can think of:
Use delegated event handler on the div: Add a click handler on the div, but then only take action if the click passed through the b element.
Use a ref on the div, and then hook the click handler up in componentDidMount and componentDidUpdate (finding the b element within the div via querySelector or similar), something along these lines:
Here's an example of #1:
<div onClick={this.clickHandler} dangerouslySetInnerHTML={this.createMarkup(string)}/>
...where clickHandler is
clickHandler(e) {
// `target` is the element the click was on (the div we hooked or an element
// with in it), `currentTarget` is the div we hooked the event on
const el = e.target.closest("B");
if (el && e.currentTarget.contains(el)) {
// ...do your state change...
}
}
...or if you need to support older browsers without ParentNode#closest:
clickHandler(e) {
// `target` is the element the click was on (the div we hooked or an element
// with in it), `currentTarget` is the div we hooked the event on
let el = e.target;
while (el && el !== e.currentTarget && el.tagName !== "B") {
el = el.parentNode;
}
if (el && el.tagName === "B") {
// ...do your state change...
}
}
...and where you bind clickHandler in the constructor (rather than using a property with an arrow function; why: 1, 2):
this.clickHandler = this.clickHandler.bind(this);
Live Example:
let string = "Hello <b>Click here</b>";
class Example extends React.Component {
constructor(props) {
super(props);
this.state = {
clicks: 0
};
this.clickHandler = this.clickHandler.bind(this);
}
clickHandler(e) {
// `target` is the element the click was on (the div we hooked or an element
// with in it), `currentTarget` is the div we hooked the event on
// Version supporting older browsers:
let el = e.target;
while (el && el !== e.currentTarget && el.tagName !== "B") {
el = el.parentNode;
}
if (el && el.tagName === "B") {
this.setState(({clicks}) => ({clicks: clicks + 1}));
}
// Alternative for modern browsers:
/*
const el = e.target.closest("B");
if (el && e.currentTarget.contains(el)) {
this.setState(({clicks}) => ({clicks: clicks + 1}));
}
*/
}
createMarkup = value => {
return { __html: value };
};
render() {
const {clicks} = this.state;
return [
<div>Clicks: {clicks}</div>,
<div onClick={this.clickHandler} dangerouslySetInnerHTML={this.createMarkup(string)}/>
];
}
}
ReactDOM.render(
<Example />,
document.getElementById("root")
);
<div id="root"></div>
<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>
Here's an example of #2, but don't do this if A) You can solve the underlying problem separately, or B) #1 works:
let string = "Hello <b>Click here</b>";
class Example extends React.Component {
constructor(props) {
super(props);
this.state = {
clicks: 0
};
this.divRef = React.createRef();
this.hooked = null;
this.clickHandler = this.clickHandler.bind(this);
}
clickHandler() {
this.setState(({clicks}) => ({clicks: clicks + 1}));
}
hookDivContents() {
// Get the b element
const b = this.divRef.current && this.divRef.current.querySelector("b");
// No-op if it's not there or it's the same element we have hooked
if (!b || b === this.hooked) {
return;
}
// Unhook the old, hook the new
if (this.hooked) {
this.hooked.removeEventListener("click", this.clickHandler);
}
this.hooked = this.divRef.current;
this.hooked.addEventListener("click", this.clickHandler);
}
componentDidMount() {
this.hookDivContents();
}
componentDidUpdate() {
this.hookDivContents();
}
createMarkup = value => {
return { __html: value };
};
render() {
const {clicks} = this.state;
return [
<div>Clicks: {clicks}</div>,
<div ref={this.divRef} dangerouslySetInnerHTML={this.createMarkup(string)}/>
];
}
}
ReactDOM.render(
<Example />,
document.getElementById("root")
);
<div id="root"></div>
<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>
Refs are an "escape hatch" giving you direct DOM access. Don't use refs lightly; usually, there's a better choice.
But again: I would solve the underlying problem, whatever it is, differently.
