Javascript knowledge Extension

 

1: javascript type:

6 types: undefined null number string boolean function

7th types of objects

2: typeof Operator

Alert (typeof a) // undefined

If (typeof a = "undefined") {}// true

Typeof returns a string that is not a type and must be remembered. Therefore, the quotation marks in the above if statement cannot be left empty.

3: Name method: Use the Hungary name method to name the variable hump name method.

4: javascript this pointer prototype used

 

$ (Function (){

Alert ("aaaaaaaaaaa ");

Function sayHi (){

Alert ("hello ");

Return this;

}

Function sayHi2 (){

Alert ("hello2 ");

Return this;

}

Function Person (){

}

Person. prototype. sayHello = sayHi;

Person. prototype. sayHello2 = sayHi2;

Var marry = new Person ();

Marry. sayHello (). sayHello2 ();

});