构造函数中的JS私有函数

Question

I'm trying to see if a private function exists inside a constructor based on a string value being passed in. If it does then it should call that private function. I don't want to expose these methods outside the instance with this.intro or this.enter. Anyone know how I can call the private method based on the string value I pass in.

 function Animator(){
     this.animate = function( slide ){
                var type = slide.attr('id');
                if (typeof [type] == 'function'){
                    console.log("function");
                                       //call [type]()
                }else{
                    console.log("nope string = ", [type]);
                }

        }

        var intro = function(){
            console.log("INTRO WORKING");
        }

        var enter = function(){
            console.log("ENTER");
        }

    }

Create an instance of Animator.

var anim = new Animator();
anim.animate('$('.slide'));

the slide div's id is named after the animation type function to call inside Animator instance.

Answer 1

Inside your class you can put this command and make a visible some methods

return{
 _intro : intro
}

Answer 2

Store your private functions as properties of an object, so you can test for their existence:

var private = {
  intro: function(){
    console.log("INTRO WORKING");
  },

  enter: function(){
    console.log("ENTER");
  }
}

this.animate = function( slide ){
  var type = slide.attr('id');
  if (private[type]) {
    private[type].apply(this, slide)
  }
}

Answer 3

You could try something like this:

function Animator(){
    this.animate = function( slide ){
        var type = slide.attr('id');
        if (typeof privates[type] == 'function'){
            console.log("function");
            privates[type]();
        }else{
            console.log("nope string = ", type);
        }
    }

    var privates = {
        intro: function(){
            console.log("INTRO WORKING");
        },
        enter: function(){
            console.log("ENTER");
        }
    }
}

Testing this out like so

var x = new Animator();
x.animate({ attr:function(){ return 'intro'; } })

Succesfully prints "INTRO WORKING" on the console.