Detecting javascript version

[RobinTibbs]

is there a definitive method for detecting the javascript version or is it a matter of finding a list of what browsers support which js version?

[mainewoods]

Instead of detecting the js version available, it is much better to 'Object detection' coding:

http://www.quirksmode.org/js/support.html

if (document.images) //will return true if  'images' is supported by browser 
{
    do something with the images array
}