Test PhantomJS 1.9.7 selectors API speed for a huge DOM

benchmark.js

var page = require('webpage').create();
var content = "",
    max = 100000,
	i;

for(i = 0; i < max; i++) {
	content += '<form id="f' + i + '"><input type="hidden" name="in' + i + '" valuate"iv' + i + '"></form>';
}

page.evaluate(function(content){
	document.body.innerHTML = content;
}, content);

console.log("FORMS ADDED");

setTimeout(function(){
	var times = page.evaluate(function(max){
		var obj = {
			cssplain: 0,
			cssbyForm: 0,
			cssbyFormChild: 0,
			cssbyFormJsDomChild: 0,
			cssbyFormChildHybridChild: 0,
			cssbyFormHybridChild: 0,
			xpathplain: 0,
			xpathbyForm: 0
		},
			idx, start, el, i,
			repeat = 100;
		
		for(i = 0; i < repeat; i++){
			idx = Math.floor(Math.random()*max);
			start = (new Date()).getTime();
			el = document.querySelector('input[name="in'+idx+'"][value="iv'+idx+'"]');
			obj.cssplain += (new Date()).getTime() - start;
			
			idx = Math.floor(Math.random()*max);
			start = (new Date()).getTime();
			el = document.querySelector('#f'+idx+' input[name="in'+idx+'"][value="iv'+idx+'"]');
			obj.cssbyForm += (new Date()).getTime() - start;
			
			idx = Math.floor(Math.random()*max);
			start = (new Date()).getTime();
			el = document.querySelector('form:nth-child('+(idx+1)+') input[name="in'+idx+'"][value="iv'+idx+'"]');
			obj.cssbyFormChild += (new Date()).getTime() - start;
			
			idx = Math.floor(Math.random()*max);
			start = (new Date()).getTime();
			el = document.body.children[max-1].querySelector('input[name="in'+idx+'"][value="iv'+idx+'"]');
			obj.cssbyFormJsDomChild += (new Date()).getTime() - start;
			
			idx = Math.floor(Math.random()*max);
			start = (new Date()).getTime();
			el = document.querySelector('form:nth-child('+(idx+1)+')').querySelector('input[name="in'+idx+'"][value="iv'+idx+'"]');
			obj.cssbyFormChildHybridChild += (new Date()).getTime() - start;
			
			idx = Math.floor(Math.random()*max);
			start = (new Date()).getTime();
			el = document.querySelector('#f'+idx).querySelector('input[name="in'+idx+'"][value="iv'+idx+'"]');
			obj.cssbyFormHybridChild += (new Date()).getTime() - start;
			
			idx = Math.floor(Math.random()*max);
			start = (new Date()).getTime();
			el = document.evaluate('//input[@name="in'+idx+'" and @value="iv'+idx+'"]', document, null, XPathResult.FIRST_ORDERED_NODE_TYPE, null);
			obj.xpathplain += (new Date()).getTime() - start;
			
			idx = Math.floor(Math.random()*max);
			start = (new Date()).getTime();
			el = document.evaluate('//form[@id="f'+idx+'"]//input[@name="in'+idx+'" and @value="iv'+idx+'"]', document, null, XPathResult.FIRST_ORDERED_NODE_TYPE, null);
			obj.xpathbyForm += (new Date()).getTime() - start;
		}
		for(var type in obj) {
			obj[type] /= repeat;
		}
		return obj;
	}, max);
	console.log("TIMES");
	for(var type in times) {
		console.log(type+":\t"+times[type]);
	}
	phantom.exit();
}, 0); // just in case the content is not yet evaluated

output

cssbyForm:                  29.55
cssbyFormChild:             29.97
cssbyFormChildHybridChild:  11.51
cssbyFormHybridChild:       10.17
cssbyFormJsDomChild:        11.73
cssplain:                   29.39
xpathbyForm:                206.66
xpathplain:                 207.05