index = angle1 + angle2 | 0 Will keep things an integer. The | requires casting to int, the 0 makes it a no-op after the cast. This is from asm.js which had

index = angle1 + angle2 | 0 Will keep things an integer. The | requires casting to int, the 0 makes it a no-op after the cast. This is from asm.js which had to emulate integers so they looked through what it would take http://asmjs.org/spec/latest/ http://asmjs.org/spec/latest/