Description of defining private methods in javascript (private method)_javascript skills

I once thought that in the world of JavaScript, all methods are public, and it is impossible to technically define a private method. Today I discovered again: In fact, I was wrong!

Copy code The code is as follows:

var Person = function(name,sex){
this.name = name;
this. sex = gender; ;
      alert("Private method is called! Private member value: " _privateVariable);                                                                                                                                                                                Person.prototype.sayHello = function(){
alert("Name: " this.name ", gender: " this.sex);
}

var p = new Person("Bodhi Yang Guo under the tree","male");   
p.sayHello();

//p.privateMethod();//An error will be reported here, and the private method cannot be called by the instance
alert(p._privateVariable);//Display: undefined


Explanation: The function defined in the constructor of the class is a private method; and the variables declared with var in the constructor are also equivalent So private variables. (However, it is different from the concept of private members in strongly typed languages ​​such as C#. For example, it cannot be called in methods other than non-constructors)

Similarly, we can also implement encapsulation of properties like set and get




Copy code

The code is as follows:

var Person = function(){  var salary = 0.0; this.setSalary = function(value){  salary = value; }

this.getSalary = function(){

return salary;
}
}

var p = new Person();

p.setSalary(1000) ;
alert(p.getSalary());//Return 1000
alert(p.salary);//Return undefined


Note: "Variable scope" in js , "Function call context (this)", "closure", and "prototype chain" are indeed worth spending some time to understand. After these hurdles have been overcome, I believe that the level of JS novices (such as myself) It will also reach a new level.