Javascript & |

Javascript & |

I have no idea about writing articles recently. I feel that there are always endless tasks. However, I started to study Titanium over the past few days and found that its official MVC Framework (Alloy) is still quite good. At the beginning, I learned little about the code, so I haven't studied it in detail. Later I found that the official CodeStrong is a set of very good learning code. As long as I read the entire set of code, I believe the use of Alloy will basically be ~

While looking at its source code, it is found that many places use the following usage:

$.clouds && ($.index.add($.clouds));

I didn't quite understand it at the beginning. After all, I usually used a little bit of it. After I got to google, I realized that this method was very convenient and easy to use (in fact, this method is also widely used in jquery's source code ). The following is a reference to the online explanation & | an alternative usage in javascript:

A () & B (): If true is returned after a () is executed, B () is executed and the value of B is returned. If false is returned after a () is executed, then the entire expression returns the value of a (), and B () is not executed;

A () | B (): If true is returned after a () is executed, the entire expression returns the value of a (). B () is not executed. If a () is executed () if false is returned, B () is executed and the value of B () is returned;

& The priority is higher than |

It is quite clear after reading it. Let's look at the specific code:

Alert (1 & 3 | 0) & 4); // Result 4 ① alert (1 & 3 | 0 & 4 ); // result 3 ② alert (0 & 3 | 1 & 4); // Result 4 ③

Analysis:
Statement ①: 1 & 3 returns 3 => 3 | 0 returns 3 => 3 & 4 returns 4
Statement ②: Execute 1 & 3 first, return 3, return 0 in execution 0 & 4, and finally compare 3 | 0 returns 3
Statement ③: Execute 0 & 3 first, return 0, return 4 in execution 1 & 4, and finally compare 0 | 4 returns 4

Note: All integers other than 0 are true, and "undefined, null, and null" is false.

I think javascript is really flexible ~~

How to enable JavaScript?

The javascript script is forbidden by your browser!

"Menu bar of the browser" -- "Tools" option -- "Internet" option -- "security" option -- "Custom Level ***" option --"
Find the "script" column and select "enable" for "Java applets "!
Or select "enable" for all "Java applets" in the "script" column "!

(This is also the case with my machine. Just do what I do.) Yes!
Reference: zhidao.baidu.com/question/2928239.html

In javascript! = What do you mean?

In Javascript! = Indicates strictly not equal. In JavaScript, unll and undefined are not the same. When used in if, they are both false. And null = undefined is true, but null = undefined is false, so null! = Undefined // return true.