& |

 

Under normal circumstances&&And|This is relatively simple and will not be discussed here.

 

Prepare two objects for the following discussion.

 

VaRAlice = {

Name:"Alice",

Tostring:Function(){

Return This. Name;

}

}

 

VaRSmith = {

Name:"Smith",

Tostring:Function(){

Return This. Name;

}

}

 

in JavaScript , for && not only available for Boolean type, it does not only return Boolean type result.

L If the first operand is Boolean type, and the value is false , then return directly false .

LIf the first operand isBooleanType, and the value isTrueAnd the other operand isObjectType, the object is returned.

LIf both operands areObjectType. The second object is returned.

LIf any operand isNull, Then, returnNull.

LIf any operand isNan, Then returnNan.

LIf any operand isUndefinded, Then returnUndefined.

 

 

Alert (False& Alice); // false

Alert (True& Alice); // Alice

 

Alert (Alice & Smith); // Smith

Alert (Smith & Alice); // Alice

 

Alert (Null& Alice); // null

Alert (Nan & Alice); // Nan

Alert (undefined & Alice); // undefined

Alert (Alice & undefined); // undefined

 

For|It is not only usedBooleanType, not only returnsBooleanType.

In fact,Null,Undefined,NanWill be viewedFalse. The object is treatedTrue.

 

L If the first operand is Boolean type, and the value is true , Returns true .

L If the first operand is Boolean type, and the value is false , the second operand is Object , the Object object is returned.

LIf both operands areObjectType, the first object is returned.

LIf both operands areNull, Then, returnNull.

LIf both operands areNan, Then returnNan.

LIf both operands areUndefined, Then, returnUndefined.

 

Alert (False| Alice); // Alice

Alert (True| Alice); // true

 

Alert (Alice | Smith); // Alice

Alert (Smith | Alice); // Smith

 

Alert (Null| Alice); // Alice

Alert (Alice |Null); // Alice

Alert (Null|Null); // Null

 

Alert (Nan | Alice); // Alice

Alert (Alice | Nan); // Alice

Alert (Nan | Nan); // Nan

 

Alert (undefined | Alice); // Alice

Alert (Alice | undefined); // Alice

Alert (undefined | undefined); // undefined