Take a look what happens if you write something simple, like "a[5]=1": http://es5.github.io/#x15.4.5.1 http://es5.github.io/#x15.4.5.1 Or "a > b": http://es5.g

Take a look what happens if you write something simple, like "a[5]=1": http://es5.github.io/#x15.4.5.1 http://es5.github.io/#x15.4.5.1 Or "a > b": http://es5.github.io/#x11.8.5 http://es5.github.io/#x11.8.5 This, in turn, causes all sorts of weird behavior nicely described at https://www.destroyallsoftware.com/talks/wat https://www.destroyallsoftware.com/talks/wat