Toggling font awesome Icon using React - reactjs

Question

I want to toggle a fontAwesome icon class name on click. When clicked, the icon should change the color and also call a service which adds an object to a favorite list in the server (hence, why I use e.currentTarget: I need to remember which icon was clicked). This code works on the first click, but fails to change the class back on the second click (doing an inspect, it says the FA´s classname equals "Object object"). Any idea how I could fix it?
<FontAwesomeIcon onClick={this.ToggleClass} size={"sm"} icon={faHeart} />
ToggleClass = (e) => {
const heart = {
color: "#E4002B",
}
const clicked = {
color: "#E4002B",
background: "red"
}
if (e.currentTarget.className.baseVal != heart && e.currentTarget.className.baseVal != clicked) {
return e.currentTarget.className.baseVal === clicked;
#Callservicehere
}
else if (e.currentTarget.className.baseVal === clicked) {
e.currentTarget.className.baseVal = heart;
#callservicehere
}
}

Answer 1

You're not thinking in React yet :)
Accessing the event target and imperatively manipulating the DOM bypasses React's rendering - you might as well just be using jQuery. Not that there's anything bad about that, but it's not the right way to go about things in React.
In React, if you need to change the DOM in response to user interaction you do it in the render method, i.e. output different JSX based on the component's current state or props.

Answer 2

A couple things that might help here:
clicked and heart are both objects which means that you cannot compare them without using a deep comparison method.
var a = { id: 1 }
var b = { id: 1 }
console.log(a == b) //false
console.log(a === b) //false
If you want to compare them, you can convert them both to strings using the toString() method
heart.toString() === clicked.toString()
In your first if condition, it looks like you're returning a true/false value instead of assigning a desired classname to your target.
return e.currentTarget.className.baseVal === clicked // true/false
e.currentTarget.className.baseVal = clicked // assigned
You could also take the approach of keeping your classnames as strings and adding your styled objects inside of css
class MysteryComponent extends React.Component {
state = {
className: 'heart'
}
toggleClass = (e) => {
if (this.state.className === 'heart') {
this.setState({ className: 'clicked' })
} else if (this.state.className === 'clicked') {
this.setState({ className: 'heart' })
}
}
render() {
return (
<div className={this.state.className}>
<FontAwesomeIcon onClick={this.toggleClass} size={"sm"} icon={faHeart} />
</div>
)
}
}
// css
.heart {
color: "#E4002B";
}
.clicked {
color: "#E4002B";
background: "red";
}

Answer 3

I see. You want to fill/unfill the color of the heart as the user clicks. The reason why the results are not meeting your expectations is because of the event.targets are especially funky with FontAwesome. You may think you're clicking on it, but it manipulates the DOM in a way that when you try extract the className, it's value is often inconsistent.
This is why everyone is recommending that you make use of React's state. The logic that determines how elements are styled is now more controlled by the component itself instead of the FontAwesome library. Consider the code below, we only care about whether the item was clicked, not what class it initially has.
class Example extends React.Component{
state = {
clicked: false
}
handleOnCLick = () => {
this.setState({
clicked: !this.state.clicked
})
}
render(){
var clicked = this.state.clicked
return(
<button onClick={this.handleOnClick}>
<i
class={ clicked ? "fas fa-heart" : "fas fa-circle"}
</i>
</button>
)
}
}