Javascript Chrome:为什么批量更改样式(cssText)比以单个(.style.property)方式更改慢?
在《高性能Javascript》(High Performance Javascript)一书中,我读到了关于最小化重绘和回流的内容,批量DOM更改可以带来更好的性能,比如使用:Javascript Chrome:为什么批量更改样式(cssText)比以单个(.style.property)方式更改慢?,javascript,css,google-chrome,performance-testing,Javascript,Css,Google Chrome,Performance Testing,在《高性能Javascript》(High Performance Javascript)一书中,我读到了关于最小化重绘和回流的内容,批量DOM更改可以带来更好的性能,比如使用: var el = document.getElementById('mydiv'); el.style.cssText = 'border-left: 1px; border-right: 2px; padding: 5px;'; 而不是 var el = document.getElementById('mydiv
var el = document.getElementById('mydiv');
el.style.cssText = 'border-left: 1px; border-right: 2px; padding: 5px;';
而不是
var el = document.getElementById('mydiv');
el.style.borderLeft = '1px';
el.style.borderRight = '2px';
el.style.padding = '5px';
我在Chrome上做了一个测试,但结果正好相反,下面是我的测试代码:
var ie = (function(){
var undef, v = 3, div = document.createElement('div');
while (
div.innerHTML = '<!--[if gt IE '+(++v)+']><i></i><![endif]-->',
div.getElementsByTagName('i')[0]
);
return v> 4 ? v : undef;
}());
// First insert 100*100 element
var total = 100 * 100;
var round = 100 * 100;
var body = document.querySelector("body");
if (ie) {
total = round = 100 * 10;
}
var createElement = function (id) {
var div = document.createElement("div");
div.setAttribute("id", "id-" + id);
return div;
}
for (var i = 0; i <= total; i++) {
body.appendChild(createElement(i));
}
// Then change style in random
function randomFromInterval(from, to) {
return Math.floor(Math.random() * (to-from+1)+from);
}
function randomWidth() {
return randomFromInterval(0, 200) + "px";
}
function randomHeight() {
return randomFromInterval(0, 200) + "px";
}
function randomColor() {
var r = randomFromInterval(0, 255),
g = randomFromInterval(0, 255),
b = randomFromInterval(0, 255);
return "rgb(" + r + ", " + g + ", " + b + ")";
}
var time = +new Date();
for (var i = 0; i <= round; i++) {
var id = randomFromInterval(0, total);
var div = document.querySelector("#id-" + id);
// The `slower` way...but it is faster, use less time
div.style.width = randomHeight();
div.style.height = randomWidth();
div.style.backgroundColor = randomColor();
// var text = "width: " + randomWidth() + "; height: " + randomHeight() + "; background: " + randomColor() + ";"
// div.style.cssText = text;
}
console.log(+new Date() - time);
var ie=(函数(){
var undef,v=3,div=document.createElement('div');
当(
div.innerHTML=“”,
div.getElementsByTagName('i')[0]
);
返回v>4?v:未定义;
}());
//第一次插入100*100元素
var总计=100*100;
var round=100*100;
var body=document.querySelector(“body”);
如果(即){
总计=四舍五入=100*10;
}
var createElement=函数(id){
var div=document.createElement(“div”);
div.setAttribute(“id”、“id-”+id);
返回div;
}
对于(var i=0;i我可以问一下您是如何测试这一点的吗
您是否已将测试用例输入,例如la
可用的信息全面表明vs,在执行测试时,我似乎无法复制您注意到的结果