Test the efficiency of global variables, function variables, and constant expressions in JavaScript

Source: Internet
Author: User

<Html> <body> </ptml>
[Ctrl + A select all Note: If you need to introduce external Js, You need to refresh it to execute]
Note: During this test in IE, you need to change the "Maximum number of script steps" of IE first ":
[HKEY_CURRENT_USER \ Software \ Microsoft \ Internet Explorer \ Styles]
"MaxScriptStatements" = dword: ffffffff
In this case, the validity rate of local variables in the function is much higher than that of global variables or constant expressions. The attribute efficiency is terrible. In Firefox and Safari, Billy is still using global variables many times slower.
Using string constants directly is faster than using global variables, but creating regular expressions is much slower than using global variables.
Looking at the numbers, we can also find that in Google Chrome, Opera, and IE, there is little difference between using attributes and using global variables (Opera may be caused by its garbage collection mechanism ), from this perspective, the so-called global variables in these three browsers may be the attributes of global objects.

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