Implement a single function to set and get the value of All Private Variable in JavaScript Closures

Question

I have a function which has some variable since they are inside a function, they are local to function hence private. Now I may have many such variable, inorder to set a value and get the variable value from outside, I have to write set and get for every private variable. Is there anyway in javascript to have common function for getting and setting all private variable(PrivateOne and PrivateTwo).

        privateClosure = (function(){
        var PrivateOne;
        var PrivateTwo;
        setPrivate = function(VariableName,Value)
        {
        VariableName = Value;
        }
        getPrivate = function(VariableName)
        {
        return VariableName;
        }
        return{setPrivate,getPrivate};
        })();
        // I want to do something like this
        privateClosure.setPrivate(PrivateOne,10);
        privateClosure.getPrivate(PrivateOne);
        privateClosure.setPrivate(PrivateTwo,20);
        privateClosure.getPrivate(PrivateTwo);
        //Only one Function for all the private variable in closure.



    Is there anyway in javascript to have common function for getting and setting all private variable(PrivateOne and PrivateTwo).

It is not clear from your question what exactly are you trying to accomplish. — Tanveer Badar, Aug 12 '17 at 09:32

Jonas Wilms · Answer 1 · 2017-08-12T10:37:09.970

1

You could closure a Map:

 var data = (function(){
   var lookup = new Map();

   return {
     get(v){
       return lookup.get(v);
      },
      set(a,v){
       return lookup.set(a,v);
      }
   }
 })();

So you can do:

 data.set("a",1);
 alert( data.get("a"));

edited Aug 12 '17 at 10:37

answered Aug 12 '17 at 09:42

Jonas Wilms

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score 0 · Answer 2 · answered Aug 12 '17 at 11:47

Sure there is: eval does everything you want¹.

const privateVars = (function(){
    var privateOne;
    var privateTwo;
    return {
        setPrivate(variableName, value) {
            eval(`(v) => { ${variableName} = v; }`)(value);
        },
        getPrivate(variableName) {
            return eval(variableName);
        };
    }
 }());

_{1: …and is, of course, totally unreasonable. Don't use this.}

However, if you want something for

getting and setting all private variables

I wonder why they are private at all and you don't just use an object with public properties.

Implement a single function to set and get the value of All Private Variable in JavaScript Closures

2 Answers2