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Asm.js Chess Battle

Updated: at 06:10 AM

Watch a chess duel between ASM and vanilla JavaScript. Browsers with ASM support show crushing victories over the vanilla engine!

Microsoft matches two chess engines against one another!

They are identical in nearly every detail, including source code! The only difference is that one has a flag set to be interpreted as asm.js, a specialized and strict JavaScript subset that allows JavaScript engines to employ specialized compilation to dramatically speed up execution.

Each turn is limited to 200ms – because the asm.js-optimized engine has a significant performance advantage, it can evaluate more moves per turn and has a substantially higher likelihood of victory. You can adjust the turn length and other variables in the demo to see how they affect the outcome of the game.

Try it now at!