Convert working VueJS component to ReactJS - reactjs

Question

I have a Vue component that works just fine. Now I'm trying to convert that code to ReactJS equivalent. My attempt on React
var ticksArray = Array.apply(null, {length: 27}).map(Number.call, Number);
export default class Timer extends Component {
constructor(props) {
super(props);
this.state = {
angle:250,
minangle:0,
maxangle:270,
xDirection:"",
yDirection:"",
oldX:0,
dragging: false
}
}
onMousedown(){
this.setState({dragging : true});
}
onMouseup(){
this.setState({dragging : false});
}
onMousemove(e){
if(!this.state.dragging)
return;
this.setState({
xDirection : this.state.oldX < e.pageX ? 'right' : 'left',
oldX:e.pageX,
yDirection: this.state.xDirection === 'left' ? 'down' : 'up'
});
if(this.state.yDirection === 'up' && this.state.angle + 2 <=
this.state.maxangle)
this.setState({angle:this.state.angle += 2})
else if(this.state.yDirection === 'down' && this.state.angle - 2 >=
this.state.minangle)
this.setState({angle:this.state.angle -= 2})
}
knobStyle(){
return {
'transform':'rotate('+this.state.angle+'deg)'
}
}
activeTicks(){
return (Math.round(this.state.angle / 10) + 1);
}
currentValue(){
return Math.round((this.state.angle/270)*100) + '%'
}
componentDidMount(){
document.addEventListener('mouseup',this.state.onMouseup)
document.addEventListener('mousemove',this.state.onMousemove)
}
render() {
var tickDivs = ticksArray.map(function(item) {
return (
<div key={item} className="tick"></div>
);
});
return (
<div id="timer">
<div className="knob-surround">
<div className="knob"></div>
<span className="min">Min</span>
<span className="max">Max</span>
<div className="ticks" className="n <= activeTicks ?
'activetick' : ''">
{tickDivs}
</div>
</div>
</div>
);
}
}
It's not working. I'm missing something. I'm assuming the problem lies in this code bit.
<div className="ticks" className="n <= activeTicks ?
'activetick' : ''">
Please help fix this.

Answer 1

Add this here instead of comment:
React uses the following syntax:
className={n <= activeTicks ? 'activetick' : ''}
In componentDidMount you assign handlers in a wrong way, should be like:
document.addEventListener('mouseup', this.onMouseup)
Note here that handler is not a part of your state. And the corresponding definition of the handler:
private onMouseup = () => {...}
The reason to store reference for the event handler instead of having class method - see in #3
Do not forget to unsubscribe your event handlers in componentWillUnmount like this:
window.removeEventListener("mouseup", this.onMouseup);
UPDATE:
Here is an example working without using arrow functions: https://jsfiddle.net/6dnrLw4n/4/