Mozilla spidermonkey is the ECMA reference implementation. Do Opera and WebKit support javascript 1.7, 1.8, 1.9?
To be fair, ECMA 262 edition 3 reference implementation is SpiderMonkey's JS 1.5. The changes in 1.7, 1.8, and 1.9 have not been standardized. Regardless of whether these changes are slated to be part of edition 4, the previous sentence holds true, and the other vendors shouldn't be faulted for not supporting these.
Furthermore, SpiderMonkey does have some deviations from the standard, albeit incredibly minor.
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To be fair, ECMA 262 edition 3 reference implementation is SpiderMonkey's JS 1.5. The changes in 1.7, 1.8, and 1.9 have not been standardized. Regardless of whether these changes are slated to be part of edition 4, the previous sentence holds true, and the other vendors shouldn't be faulted for not supporting these.
Furthermore, SpiderMonkey does have some deviations from the standard, albeit incredibly minor.