6 div 135 or 246 interval One second turns display effect _javascript tips

In a technical group to see a gentleman raised the following question:

A June

6 div interval One second turns to parity display. Like 1351 seconds, 246, and then 135 loops.

A June

Require code to be dapper

B-June

Copy Code code as follows:

var a = document.getElementsByTagName (' div ');
var B = false;
SetInterval (function () {
for (var i = 0; i < 6; i++)
A[i].style.display = ((i & 1) ^ b)? ' Block ': ' None ';
b =!b;

}, 1000);

A June
D-June, this is a good efficiency.
I'm not as simple as ABCD.

Copy Code code as follows:

j + +; for (var i = 0; i < 6; i++) o[i].style.display = [[' Blocks ', ' none '], [' None ', ' Block ']][j & 1][i & 1];

D-June
With arrays, it also affects efficiency


Read not to sigh D June's method is really good, if I really can't think of such an efficient method.