Press n or j to go to the next uncovered block, b, p or k for the previous block.
| 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 | import React, { PureComponent } from 'react';
import PropTypes from 'prop-types';
import smoothscroll from 'smoothscroll-polyfill';
import ReactGA from 'react-ga';
import { withScrolling } from '../../lib/ScrollContext';
import ScrollUpIcon from '../Icons/ScrollUpIcon';
import styles from './TOCButton.scss';
smoothscroll.polyfill();
class TOCButton extends PureComponent {
static propTypes = {
scrollTop: PropTypes.number.isRequired,
};
constructor(props) {
super(props);
this.state = {
display: false,
};
}
componentDidMount() {
this.timer = setInterval(() => { this.updateDisplay(); }, 30);
}
updateDisplay = () => {
const { display } = this.state;
const { scrollTop } = this.props;
const scrolled = scrollTop !== 0;
if (scrolled !== display) {
this.setState({
display: scrolled,
});
}
}
handleScrollToTop = (event) => {
event.preventDefault();
window.scrollTo({
top: 0,
left: 0,
behavior: 'smooth',
});
const cookiesAccepted = localStorage ? localStorage.getItem('cookiesAccepted') : false;
if (!cookiesAccepted) {
return;
}
ReactGA.event({
category: 'Click',
action: 'TOC',
label: 'Top of Content',
});
}
render() {
const { display } = this.state;
return (
<div
className={`${styles.button}${display ? ` ${styles['button--visible']}` : ''}`}
>
<button
className={styles.button__button}
onClick={this.handleScrollToTop}
type="button"
>
<ScrollUpIcon className={styles.button__icon} />
</button>
</div>
);
}
}
export default withScrolling(TOCButton);
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