資料來(lái)源：MSDN
[英文原文]
msdn.microsoft.com/library/en-us/dnwebgen/html/dhtmlperf.asp?frame=true
[中文譯文]
www.microsoft.com/china/msdn/msdnonline/features/articles/dhtmlperf.asp
1.盡量使用同一個(gè)腳本函數(shù)來(lái)改變HTML內(nèi)容。如果有多個(gè)事件觸發(fā)，盡量只改變同一個(gè)地方。
2.盡量把內(nèi)容集中起來(lái)一次更新。如果不是特別需要有HTML的內(nèi)容，盡量使用innerText代替innerHTML
Slow:
divUpdate.innerHTML = "";
for ( var i=0; i<100; i++ )
{
divUpdate.innerHTML += "<SPAN>This is a slower method! </SPAN>";
}
Fast:
var str="";
for ( var i=0; i<100; i++ )
{
str += "<SPAN>This is faster because it uses a string! </SPAN>";
}
divUpdate.innerHTML = str;
3.更新文本內(nèi)容時(shí)盡量使用innerText而不是DOM的createTextNode
Slow:
var node;
for (var i=0; i<100; i++)
{
node = document.createElement( "SPAN" );
node.appendChild( document.createTextNode( " Using createTextNode() " ) );
divUpdate.appendChild( node );
}
Fast:
var node;
for (var i=0; i<100; i++)
{
node = document.createElement( "SPAN" );
node.innerText = " Using innerText property ";
divUpdate.appendChild( node );
}
4.盡量使用createElement 和 insertAdjacentElement 方法，而不是 insertAdjacentHTML
Slow:
for (var i=0; i<100; i++)
{
divUpdate.insertAdjacentHTML( "beforeEnd", "<SPAN> Uses insertAdjacentHTML() </SPAN>" );
}
Fast:
var node;
for (var i=0; i<100; i++)
{
node = document.createElement( "SPAN" );
node.innerText = " Uses insertAdjacentElement() ";
divUpdate.insertAdjacentElement( "beforeEnd", node );
}
5.在數(shù)目巨大的情況下，盡量使用innerHTML 來(lái)添加項(xiàng)
Slow:
var opt;
divUpdate.innerHTML = "<SELECT ID='selUpdate'></SELECT>";
for (var i=0; i<1000; i++)
{
opt = document.createElement( "OPTION" );
selUpdate.options.add( opt );
opt.innerText = "Item " + i;
}
Fast:
var str="<SELECT ID='selUpdate'>";
for (var i=0; i<1000; i++)
{
str += "<OPTION>Item " + i + "</OPTION>";
}
str += "</SELECT>";
divUpdate.innerHTML = str;
Faster:
var arr = new Array(1000);
for (var i=0; i<1000; i++)
{
arr[i] = "<OPTION>Item " + i + "</OPTION>";
}
divUpdate.innerHTML = "<SELECT ID='selUpdate'>" + arr.join() + "</SELECT>";
6.使用DOM來(lái)創(chuàng)建表格比TOM(insertRow,insertCell)好的多
Slow:
var row;
var cell;
for (var i=0; i<100; i++)
{
row = tblUpdate.insertRow();
for (var j=0; j<10; j++)
{
cell = row.insertCell();
cell.innerText = "Row " + i + ", Cell " + j;
}
}
Fast:
var row;
var cell;
var tbody = tblUpdate.childNodes[0];
tblUpdate.appendChild( tbody );
for (var i=0; i<100; i++)
{
row = document.createElement( "TR" );
tbody.appendChild( row );
for (var j=0; j<10; j++)
{
cell = document.createElement( "TD" );
row.appendChild( cell );
cell.innerText = "Row " + i + ", Cell " + j;
}
}
7.通用的操作，盡量放在一個(gè)單獨(dú)的外部腳本文件里
8.約束你的動(dòng)態(tài)屬性（指setExpression的用法）
9.使用數(shù)據(jù)綁定來(lái)顯示你的資料，你可以使用排序、過(guò)濾等操作來(lái)提供不同視圖，但只需要訪問(wèn)一次服務(wù)器(減少頻繁訪問(wèn)服務(wù)器的問(wèn)題)
10.不要把自定義的屬性加到document對(duì)象上，這會(huì)使得每次讀取該屬性時(shí)進(jìn)行額外的重算。推薦加在window對(duì)象上
Slow:
for (var i=0; i<1000; i++)
{
var tmp;
window.document.myProperty = "Item "+i;
tmp = window.document.myProperty;
}
Fast:
for (var i=0; i<1000; i++)
{
var tmp;
window.myProperty = "Item "+i;
tmp = window.myProperty;
}
11.盡量直接使用style對(duì)象來(lái)改變HTML對(duì)象外觀，而不是className或者跟clas關(guān)聯(lián)的styleSheet對(duì)象
12.在訪問(wèn)textrange對(duì)象的父對(duì)象(指parentElement方法的返回值)時(shí)，先collapse合并range，尤其是復(fù)雜的range
13.先插入對(duì)象，然后添加它的內(nèi)容
Slow
(1).create <TR>
(2).create <TD>
(3)create TextNode
(4)insert TextNode into <TD>
如前所述，這里用innerText會(huì)更快
(5)insert <TD> into <TR>
(6)insert <TR> into TBODY
Fast
(1)create <TR>
(2)create <TD>
(3)create TextNode
如前所述，這里用innerText會(huì)更快
(4)insert <TR> into TBODY
(5)insert <TD> into <TR>
(6)insert TextNode into <TD>
如前所述，這里用innerText會(huì)更快
14.用posLeft,posTop,posWidth,posHeight來(lái)代替left,top等，減少字符串->數(shù)值的轉(zhuǎn)換
15.盡可能少的使用定時(shí)器(指setTimeout,setInterval這些)，而在同一個(gè)定時(shí)器里對(duì)所有要變化的對(duì)象進(jìn)行操作
