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The point is that JavaScript developers shouldn’t have to detect and workaround such issues. JavaScript should work the same across all implementations. We believe this is the first step in making JavaScript better. To make it possible to achieve such implementation conformance, the first step is knowing where the divergences are. We in the JScript team are looking into where various browser based implementations diverge, where our engine is incorrect in its interpretation of the specification, what if any de facto compatibility conventions have been reached, and the value of codifying such conventions into the standard. We’ve published the first draft of JScript Deviations from ES3 as a starting point.