Accessing variable in another function, returns undefined - JavaScript

问题

I am trying to access a variable which exists in another function, but I am not able to, it gives me undefined for the function through which (getMess() as below) I am doing that. As per the code below, I want the "value1" accessed through myfunction1, as shown below. Code:

var namespace ={
    myfunction1: function(){
        namespace.myfunction2.getMess();   // I need to access value1 here in this function
    },

    myfunction2: function(message1,message2){
        var value1 = message1;
        var value2 = message2;
        return{
          getMess: function(){ return value1;}
          getLab: function() { return value2;}
        }
    }
}

namespace.myfunction2("hello","bye"); // this basically just sets the 2 values on page load

I just posted another question with the original problem : Read resource file entry in javascript - MVC application

回答1:

You could do:

myfunction2: function(message1,message2){

    var value1 = message1;
    var value2 = message2;

    namespace.myfunction2.getMess: function(){ return value1;}
    namespace.myfunction2.getLab: function() { return value2;}
}

but that's pretty awful (assigning properties to a function object). Better to refactor the whole thing using the module pattern to emulate private and privileged members.

e.g.

var namespace = (function() {

    // Private members
    var value1, value2;

    return {

      // Privileged methd to read private member values
      fn1: function() {
        return namespace.fn2.getMess1();
      },

      // Privileged methods to set and get private member values
      fn2: {
        setMess: function(message1, message2) {
          value1 = message1;
          value2 = message2;
        },

        getMess1: function() {
          return value1;
        },

        getMess2: function() {
          return value2;
        }
      }
    }
}());

namespace.fn2.setMess("hello","bye");

alert(namespace.fn1()); // hello

回答2:

This seems very strange to me, but first off you were retuning an object and missing a , inbetween the 2 functions you were trying to return.

var namespace ={
    myfunction1: function(){
        var jamie = namespace.myfunction2("hello","bye");   // save returned value so we can use them later.
        console.info(jamie.getMess); //as we already executed the value just refer to them
    },

    myfunction2: function(message1,message2){
        var value1 = message1;
        var value2 = message2;
        return{
          getMess: function(){ return value1;}(), //return self executing functions to return values without the need to run them again.
          getLab: function(){ return value2;}()
        }
    }
}
namespace.myfunction1();

While I'm still not sure what you're trying to achieve this is how I would pass values between 2 functions whilst not declaring variables to namespace and just assigning values globally that way.

来源：https://stackoverflow.com/questions/19446634/accessing-variable-in-another-function-returns-undefined-javascript

标签

javascript

function

closures

scope

scoping