[knd775]

Even better is 'is-even'. It depends on 'is-odd' and this is the entire thing:

  var isOdd = require('is-odd');
  
  module.exports = function isEven(i) {
    return !isOdd(i);
  };

[dingaling]

What does it return for zero?

[rys]

(Thankfully?) it gets that right

[tlrobinson]

Zero is even.