Javascript操作在各浏览器下的性能比较

目前，使用Ajax技术的应用程序越来越多，同时伴随而来的是javascript在各浏览器下的性能问题。近期，coachwei对许多不同的Javascript操作在各浏览器下的性能表现作了快速的比较与小结。根据他提供的测试结果，可以让我们在编写javascript时尽量减少或避免使用那些性能开销较大的javascript操作。

以下是对测试结果的引用，测试环境:
·         Windows XP SP2,  DELL Latitude D820,  2GB RAM, 1.66GHz Dual CPU
·         IE 7.0.5730.11
·         FireFox 2.0.0.11
·         Safari 3.0.2 (522.13.1)
·         Application: http://www.rockstarapps.com/samples/performance/

	Internet Explorer 7		FireFox		Safari
Description	Time (ns)	% of base	Time (ns)	% of base	Time (ns)	% of base
Normal Empty function call (Base Operation)	4.7	100%	3.9	100%	1.6	100%
Basic Function Calls
Function call using function.call(this)	5.5	116%	2.4	60%	1.6	100%
Normal Empty function using apply	5.5	117%	7.0	179%	2.4	152%
Normal Empty function using apply with 3 parameters	7.0	149%	7.1	181%	2.4	152%
Eval a function	172.0	3660%	546.0	14000%	9.4	603%
Eval an object	94.0	2000%	749.0	19205%	22.7	1461%
Basic Operations
Access Properties through a getter	13.3	282%	6.3	160%	5.5	352%
Access Properties directly	4.7	100%	3.2	81%	2.4	152%
Simple string concatenation	4.7	100%	2.3	59%	1.6	100%
Simple string compare	3.9	83%	2.4	60%	0.8	48%
Change string to upper case	11.7	249%	3.9	100%	4.7	303%
Replace string reg expression	12.5	266%	7.1	181%	9.4	603%
String concat with integer	7.1	150%	4.7	119%	2.4	152%
String concat with float	6.3	133%	4.7	121%	2.4	152%
Index of Bob in string, not found, length = 71	6.3	133%	6.3	160%	2.4	152%
Match of Bob in string, not found, length = 71	14.9	316%	25.0	640%	3.9	252%
charAt(10) in string	11.7	249%	6.3	160%	3.1	200%
Create object constructor initialized	11.7	249%	23.4	600%	3.2	203%
create simple object	8.6	182%	23.4	600%	2.4	152%
		0%
Variable declaration	4.0	84%	2.3	59%	0.8	48%
Multiple variable declaration, multiple var	3.9	83%	2.4	60%	2.4	152%
Multiple variable declaration single var	3.9	83%	2.4	60%	1.6	100%
Variable declaration set to null	3.9	83%	2.4	60%	1.6	100%
		0%
Variable assignment++	4.7	100%	5.5	140%	1.6	103%
Variable assignment + 1	5.5	116%	7.1	181%	1.6	100%
Four levels of property access	5.5	116%	5.5	140%	1.6	100%
Three levels of property access	4.7	100%	4.7	121%	2.4	152%
Two levels of property access	4.7	100%	4.7	119%	1.6	100%
One level of property access	3.9	83%	4.7	121%	1.6	103%
		0%
Using the typeof function	3.9	83%	4.7	119%	1.6	100%
Array Operations
Array access	7.1	150%	7.0	179%	1.6	100%
Array index value change	3.9	83%	4.7	121%	1.6	103%
Empty Array index value change	8.6	183%	8.6	221%	6.3	403%
Empty Array add three values	10.2	216%	11.7	300%	3.1	200%
Empty Array with set size	11.0	233%	11.0	281%	3.2	203%
Empty Array using constructor	9.4	199%	25.8	662%	2.3	148%
Push element onto an Array	25.0	532%	6.3	160%	1.5	98%
Pop element of an Array	165.6	3523%	6.3	160%	249.7	16112%
Push element onto an Array	6.2	132%	7.1	181%	1.4	92%
Shift elements off the front of an Array	2030.0	43191%	5620.0	144103%	1250.0	80645%
Join the array into a string	125000	2659574%	47000	1205128%	16000	1032258%
Push element onto an Array	7.1	150%	7.0	179%	3.9	252%
Sorting of an Array	93.0	1979%	45.3	1162%	32.9	2119%
Math.max(7.25,7.30)	5.5	116%	4.7	121%	3.9	252%
Math.min(7.25,7.30)	5.5	117%	4.7	121%	3.2	203%
HTML DOM Operations
Change text using innerHTML	469.0	9979%	234.0	6000%	109.0	7032%
Create a text node on HTML Dom	1093.0	23255%	156.0	4000%	110.0	7097%
Change the class name of an element	422.0	8979%	47.0	1205%	109.0	7032%
getElementById	86.8	1846%	15.7	401%	3.9	252%
getElementsByTagName("div")	153.1	3257%	18.0	462%	5.5	352%
getElementsByTagName("spa")	142.2	3024%	18.8	481%	5.5	355%
getElementsByName	93.8	1995%	44.6	1142%	4.7	303%
placeDiv.getAttribute("id")	29.7	632%	46.8	1200%	5.5	352%
placeDiv.attributes["id"]	31.3	665%	225.0	5769%	6.3	403%
var atts = placeDiv.attributes; atts["id"].name	11.7	249%	18.8	482%	4.7	303%
var atts = placeDiv.attributes; atts.id.name	12.5	266%	18.8	482%	3.9	252%
Try/Catch
Function call using function.call(this)	7.1	150%	4.0	101%	2.4	152%
Try catch	7.1	150%	6.3	160%	5.5	352%
Try catch with throw	17.2	365%	7.8	200%	5.5	355%
Try catch finally	9.4	199%	7.8	200%	4.7	303%
Try catch finally with throw	16.5	350%	11.0	281%	6.3	403%
If statement and Date object
Create a date object	12.5	266%	10.2	260%	3.1	200%
Create a date object and call getDate()	28.1	598%	50.8	1303%	10.2	658%
The switch statement	4.7	99%	2.4	60%	2.4	152%
An if statement	4.0	84%	2.4	60%	2.4	152%
Simple if else	4.1	86%	2.2	56%	1.9	121%
turinary operator	3.9	83%	2.3	60%	2.0	131%
Compare of matching string ==	4.7	100%	7.1	181%	2.4	152%
Compare of matching string ===	4.7	100%	7.0	179%	2.4	152%
Compare of non-matching string	4.7	100%	3.9	100%	2.4	152%
Compare  TEST_INT == 5	4.1	86%	4.2	108%	1.7	111%
Compare  5 == 5	4.1	87%	2.0	52%	1.6	101%
Looping Performance Statistics
Loop through an array using in	10.3	219%	62.8	1610%	7.8	503%
Loop through an array using for (i++)	6.3	133%	10.6	273%	3.4	222%
Loop through an array using for (i < myArray.length)	6.2	133%	10.9	281%	3.1	201%
Loop through an array using for (i = 0; i < len; i++)	5.0	106%	4.7	120%	4.1	262%
Loop through an array using for (i = 0; i < len; i++)	5.3	113%	5.0	128%	4.1	262%
Loop through an array using while {i++}	5.3	113%	5.3	136%	4.7	302%
Loop through an array using while (i++ < len)	5.0	106%	5.0	128%	4.4	283%