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import { createElement, Component, options } from 'preact';
function getPrimes(max) {
let sieve = [],
i,
j,
primes = [];
for (i = 2; i <= max; ++i) {
if (!sieve[i]) {
// i has not been marked -- it is prime
primes.push(i);
for (j = i << 1; j <= max; j += i) {
sieve[j] = true;
}
}
}
return primes.join('');
}
function Foo(props) {
return <div>{props.children}</div>;
}
function Bar() {
getPrimes(10000);
return (
<div>
<span>...yet another component</span>
</div>
);
}
function PrimeNumber(props) {
// Slow down rendering of this component
getPrimes(10);
return (
<div>
<span>I'm a slow component</span>
<br />
{props.children}
</div>
);
}
export default class ProfilerDemo extends Component {
constructor() {
super();
this.onClick = this.onClick.bind(this);
this.state = { counter: 0 };
}
componentDidMount() {
options._diff = vnode => (vnode.startTime = performance.now());
options.diffed = vnode => (vnode.endTime = performance.now());
}
componentWillUnmount() {
delete options._diff;
delete options.diffed;
}
onClick() {
this.setState(prev => ({ counter: ++prev.counter }));
}
render() {
return (
<div class="foo">
<h1>⚛ Preact</h1>
<p>
<b>Devtools Profiler integration 🕒</b>
</p>
<Foo>
<PrimeNumber>
<Foo>I'm a fast component</Foo>
<Bar />
</PrimeNumber>
</Foo>
<Foo>I'm the fastest component 🎉</Foo>
<span>Counter: {this.state.counter}</span>
<br />
<br />
<button onClick={this.onClick}>Force re-render</button>
</div>
);
}
}
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