adding to an array from a previous function

Question

so I would like to access an an array i created in a previous function. and then in id1,id2,id3, i would Like to create a new property and give that property a value. I thought I have an idea of what I should do but what Im doing is not working. I get the error IdArray is undefined.

HTML:

        <p id="show_me"></p>
        <button onclick="ObjectArray()">click me</button>
        <p id="added"></p>
        <button onclick="Added()">Add</button>

javascript previous function:

var ObjectArray = function() {
        // object literal
        var id1 = {
            firstName: "John",
            lastName: "Doe",
            id: "12345"
        };

        // keyword new
        var id2 = new Object;
        id2.firstName = "Adam";
        id2.lastName = "Bakely";
        id2.id = "abcdef";

        // object constructor 
        function employee(first, last, id) {
            this.firstName = first;
            this.lastName = last;
            this.id = id;
        }
        var id3 = new employee("Dallas", "Star", "abc123");

        //create an array
        var IdArray = [id1, id2, id3];
}

javascript new function:

function Added(IdArray, sex){
    IdArray.push({sex : sex})
    IdArray[0].sex = "male";
    document.getElementById("added").innerHTML = IdArray[0]; 
}

im lost, so how do I access the array from the previous function and add to it?

don't think this will work like expected.. innerHTML is better with a string document.getElementById("added").innerHTML = IdArray[0] — webdeb
– webdeb, Commented Sep 12, 2015 at 22:33

StackSlave · Accepted Answer · 2015-09-12 23:21:17Z

2

You do not have access to variables in other functions, you can however access variable declared above your functions. Your real problem is a failure to understand Constructors, which will greatly benefit you in the future. Check this out:

function Employee(id, firstName, lastName, middleName){
  this.id = id; this.firstName = firstName; this.lastName = lastName;
  this.middleName = middleName;
  this.notes = [];
  this.getFullName = function(){
    var mn = this.middleName ? ' '+this.middleName : '';
    return this.firstName+mn+' '+this.lastName;
  }
  this.createNote = function(note){
    this.notes.push(note);
    return this;
  }
  this.getNotesString = function(delimiter){
    return this.notes.join(delimiter);
  }
}
var employee1 = new Employee('abc123', 'Joe', 'Schmoe');
employee1.createNote('Note You Want to Store.');
employee1.createNote('Just Another Test Note.');
var employee2 = new Employee('def456', employee1.firstName, 'Smith', 'Walter'); // notice how you access the other instance firstName
console.log(employee1.getFullName());
console.log(employee1.getNotesString('|'));
console.log(employee2.getFullName());
console.log(employee2.createNote('Note 1').createNote('Note 2').createNote('Note 3').getNotesString('|')); // by returning `this` you can access other methods in the same Constructor

edited Sep 12, 2015 at 23:21

answered Sep 12, 2015 at 23:14

StackSlave

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3 Comments

kronis72 Over a year ago

could you exlpain like Im five, what exactly is going on here, I got some idea of whats going on, but still lost.

kronis72 Over a year ago

the first function is using object constructor to create an object type "employee", which contains firstName, lastName, middleName.... then I think "this.notes=[]; creates a note object... this.getfullname creates an object function? to return full name.. unsure of how creating a var mn and then useing this.firstname+mn+ works, confused to what exactly happens here.... this.createnote function allows you to push text into the note array.... a little confused on this part and then next function.... think I may not understand the full use of "this" as well

StackSlave Over a year ago

Look into ternary expressions. this in this case refers to the individual instance of an Object, not another Object.

Saar · Accepted Answer · 2015-09-12 22:30:23Z

You need to either save the IdArray or to return it:

var IdArray;
    var ObjectArray = function() {
            // object literal
            var id1 = {
                firstName: "John",
                lastName: "Doe",
                id: "12345"
            };

            // keyword new
            var id2 = new Object;
            id2.firstName = "Adam";
            id2.lastName = "Bakely";
            id2.id = "abcdef";

            // object constructor 
            function employee(first, last, id) {
                this.firstName = first;
                this.lastName = last;
                this.id = id;
            }
            var id3 = new employee("Dallas", "Star", "abc123");

            //create an array
            IdArray = [id1, id2, id3]; //removed the var keyword, so I am using the global variable
    }

and then use it. notice I removed the var keyword so I am using the global IdArray.

Draconis · Accepted Answer · 2015-09-12 22:32:04Z

1

The variable IdArray was created inside the function, so it expires when the function ends. If you add the line

var IdArray;

before your first function that will make it global instead. Then reference to IdArray inside either function will refer to the same variable.

answered Sep 12, 2015 at 22:32

Draconis

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Comments

jonny · Accepted Answer · 2015-09-12 22:33:19Z

1

I added the IdArray as a property of the window object to give it global scope:

var ObjectArray = function() {
        // object literal
        var id1 = {
            firstName: "John",
            lastName: "Doe",
            id: "12345"
        };

        // keyword new
        var id2 = new Object;
        id2.firstName = "Adam";
        id2.lastName = "Bakely";
        id2.id = "abcdef";

        // object constructor 
        function employee(first, last, id) {
            this.firstName = first;
            this.lastName = last;
            this.id = id;
        }
        var id3 = new employee("Dallas", "Star", "abc123");

        //create an array
        window.IdArray = [id1, id2, id3];
}

answered Sep 12, 2015 at 22:33

jonny

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