Special symbols && and | |

The case of a value of false

If the logical object value is 0,-0, Null,undefined,false, "", NaN. Then the value is false.

Second, && | | The understanding

1.&& when logic and && are found, a sub-item with false is stopped and the value of the sub-item is returned

2.| | When logic or | | , when a sub-item is found to be true, it stops processing and returns the value of the sub-item

1              var NULL False | | NaN  | | 3 | | 4;   32             alert (a); 3              var b = 4  new Object ()  null  && "0";   null4              alert (b);

Three, && | | The priority level

&& priority is higher than | |

1 alert (0 | | 1 && 2 | |-0); // 2

Four, commonly used code analysis:

function Test (options) {    var//{} Converts a Boolean value to True    //  If options is true returns options   true | | True returns the preceding true    //  If the options are false back {}  }

Special symbols && and | |