Some explanation of code Following code in JavaScript equals number > 0 ? Math.floor(number) : Math.ceil(number) number |= 0 ~~number But according to my test, ~~x is much faster than Math.floor(x) for random positive double value. So you can use bit operation instead of Math.floor(x) and parseInt(x) if (block != null) blocks.set(blockPos, block); can be simplified to if (block) blocks.set(blockPos, block); or just block && blocks.set(blockPos, block); Because null in JavaScript is considered as false value, and && operator will not do things after it if things before it is a false value.