Как бы самому прогать на такой штука... сам панимаиш...

[] + [] → "" // Empty string? These are arrays!
[] + {} → [object object]
{} + [] → 0 // Why isn't the operation commutative???
{} + {} → NaN // ???
16 == [16] → true // Array converted into string, then into number
16 == [1,6] → false // But what is array converted into?
"1,6" == [1,6] → true
var arr = [];
arr.length → 0
arr[3] → "undefined" // No array bounds exception???
arr[3] = "hi";
arr.length → 4 // 4??? Only one element has been added!
arr["3"] → "hi" // Apparently "3" is coerced into a number
delete(arr[3]);
arr.length → 4 // 4??? There are no elements in the array!
arr[3] → "undefined" // 7 lines above, length was "0"!
var i = 1;
i = i + ""; // Oops!
i + 1 → "11"
i - 1 → 0
var j = "1";
++j → 2 // Okay, but...
var k = "1";
k += 1 → "11" // What???
[1,5,20,10].sort() → [1, 10, 20, 5] // Why is it sorting strings???
xs = ["10", "10", "10"];
xs.map(parseInt) → [10, NaN, 2] // ???
y = {};
y[[]] = 1;
Object.keys(y) → [""]