ricardobeat/index.html

## index.html
<!doctype html>
<body></body>

<script>
  const events = [
    'click',
    'input',
    'change',
    'mouseenter',
    'mouseleave',
    'mousemove',
    'mousedown',
    'mouseup',
    'wheel',
    'scroll',
    'select',
    'focus',
    'blur',
    'reset',
    'submit',
    'keydown',
    'keypress',
    'keyup'
  ]

  const selectors = events.map(e => `[on\\:${e}]`).join()

  const makeElement = () => {
    var ev = 'on:' + events[Math.random() * events.length | 0]
    var tag = ['button', 'textarea', 'div', 'a'][Math.random() * 4 | 0]
    var div = document.createElement('div');
    div.innerHTML = `<${tag} ${ev}="foo"></${tag}>`;
    return div.firstChild;
  }

  const movingAverage = (p,c,i) => p+(c-p)/(i+1);

  const benchOne = (name, N, fn) => {
    let times = [];
    for (let i=0; i < N; i++) {
      let start = performance.now()
      fn()
      times.push(performance.now() - start);
    }
    console.log(`${name}: ${times.reduce(movingAverage, 0).toFixed(2)}ms`);
  }

  const benchmark = (els = 10) => {
    const N = 100;
    console.group(`${els} elements:`)

    document.body.innerHTML = ''
    for (let i = 0; i < els; i++) {
      document.body.appendChild(makeElement())
    }

    benchOne('querySelector', N, () => {
      var nodes = document.querySelectorAll(selectors);
      for (let j = 0; j < nodes.length; j++) {
        nodes[j].getAttribute('on:click')
      }
      if (nodes.length !== els) throw new Error(`Node count doesn't match: ${els} x ${nodes.length}`)
    })

    benchOne('getElementsByTagName', N, () => {
      var nodes = document.getElementsByTagName('*');
      var count = 0;
      for (let j = 0; j < nodes.length; j++) {
        node = nodes[j];
        var attributes = node.attributes;
        for (let k = 0, n = attributes.length; k < n; k++) {
            attr = attributes[k];
            if (attr.name.indexOf('on:') === 0) {
                count++;
            }
        }
      }
      if (count !== els) throw new Error(`Node count doesn't match: ${els} x ${nodes.length}`)
    })

    console.groupEnd()
  }

  benchmark(1);
  benchmark(100);
</script>
	<!doctype html>
	<body></body>

	<script>
	const events = [
	'click',
	'input',
	'change',
	'mouseenter',
	'mouseleave',
	'mousemove',
	'mousedown',
	'mouseup',
	'wheel',
	'scroll',
	'select',
	'focus',
	'blur',
	'reset',
	'submit',
	'keydown',
	'keypress',
	'keyup'
	]

	const selectors = events.map(e => `[on\\:${e}]`).join()

	const makeElement = () => {
	var ev = 'on:' + events[Math.random() * events.length \| 0]
	var tag = ['button', 'textarea', 'div', 'a'][Math.random() * 4 \| 0]
	var div = document.createElement('div');
	div.innerHTML = `<${tag} ${ev}="foo"></${tag}>`;
	return div.firstChild;
	}

	const movingAverage = (p,c,i) => p+(c-p)/(i+1);

	const benchOne = (name, N, fn) => {
	let times = [];
	for (let i=0; i < N; i++) {
	let start = performance.now()
	fn()
	times.push(performance.now() - start);
	}
	console.log(`${name}: ${times.reduce(movingAverage, 0).toFixed(2)}ms`);
	}

	const benchmark = (els = 10) => {
	const N = 100;
	console.group(`${els} elements:`)

	document.body.innerHTML = ''
	for (let i = 0; i < els; i++) {
	document.body.appendChild(makeElement())
	}

	benchOne('querySelector', N, () => {
	var nodes = document.querySelectorAll(selectors);
	for (let j = 0; j < nodes.length; j++) {
	nodes[j].getAttribute('on:click')
	}
	if (nodes.length !== els) throw new Error(`Node count doesn't match: ${els} x ${nodes.length}`)
	})

	benchOne('getElementsByTagName', N, () => {
	var nodes = document.getElementsByTagName('*');
	var count = 0;
	for (let j = 0; j < nodes.length; j++) {
	node = nodes[j];
	var attributes = node.attributes;
	for (let k = 0, n = attributes.length; k < n; k++) {
	attr = attributes[k];
	if (attr.name.indexOf('on:') === 0) {
	count++;
	}
	}
	}
	if (count !== els) throw new Error(`Node count doesn't match: ${els} x ${nodes.length}`)
	})

	console.groupEnd()
	}

	benchmark(1);
	benchmark(100);
	</script>