array as data member in a class javascript

Question

I am new one in object oriented javascript and trying to define a class, that have an array as a data member. this data member of class storing objects of an other class as an array.

it will be more clear by this example

function classA(id, objB_01)
{

    this.id = id;   // data member that store a simple value
    this.arrayname = objB_01  // How multiple instance of classB is stored in this array 


}

function classB( id, name, status)
{
     this.id = id;
     this.name = name;
     this.status = status 
}

objB_01 = new classB("01", "john", "single");
objB_02 = new classB("02", "smith" "single");
objB_03 = new classB("03", "nina", "married");

now my question is how i can write classA so that single instance of classA hold an array that store mutiple object of classB

Something like this

objA = new classA("01",objB_01);
objA.arrayname = objB_02;
objA.arrayname = objB_03;

Now Finally objA contain one string and one array that store multiple objects of classB

Please point me in the right direction

meir shapiro · Accepted Answer · 2020-05-26 11:47:48Z

7

One option can be to initialize an empty array in the constructor function and also have some method to add objects to the array.

function classA (id) {
    this.id = id;
    this.array = [];

    this.add = function (newObject) {
        this.array.push(newObject);
    };
}

Then you can do this:

objA = new classA("01");
objA.add(objB_01);
objA.add(objB_02);
objA.add(objB_03);

edited May 26, 2020 at 11:47

answered Nov 8, 2014 at 18:22

meir shapiro

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Comments

Michael Angstadt · Accepted Answer · 2014-11-08 18:14:08Z

4

It might do some good to just dig into the spec docs around JavaScript Arrays.

Beyond that, to answer your question about having a classA wherein a single instance has an array of multiple classB instances - I believe you're looking for the array method .push()

As well, you'll probably want to beef up your class definition, utilizing a standard overloaded constructor pattern for JavaScript.

Something like this

function classA(id, objarray)
{

    this.id = id;   // data member that store a simple value
    this.arrayname = objarray || []; //if objarray isn't passed it'll initiate an empty array 
}
function classB( id, name, status)
{
     this.id = id;
     this.name = name;
     this.status = status 
}

objB_01 = new classB("01", "john", "single");
objB_02 = new classB("02", "smith" "single");
objB_03 = new classB("03", "nina", "married");

var objBarray = [objB_01, objB_02, objB_03];

//now you can use construct & initiate classA in two different ways
//Push each object individually
var objA = new classA("01");
objA.arrayname.push(objB_01);
objA.arrayname.push(objB_02);
objA.arrayname.push(objB_03);

//or push the entire list at once
var objA = new classA("01", objBarray);

answered Nov 8, 2014 at 18:14

Michael Angstadt

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1 Comment

user3316523 Over a year ago

you code is more realistic then any other in order to initialize a classA obj when we have not any classB obj. so we can add classB objects to this after that

guest271314 · Accepted Answer · 2014-11-08 21:28:48Z

Try

        var data = {};

        var classData = function (id, name, status, options) {
            if (options) {
                this.id = options.id;
                this[options.arrayname] = [];
            };
            if (!this.hasOwnProperty("id")) {
                throw new Error("No id set on `classData` array."
                + "Please set `id` for `classData` at `options` object")
            };
            var j = (id && name && status) ? JSON.stringify({
                id: id,
                name: name,
                status: status
            }) : false;
            j ? this[Object.keys(this).filter(function (v) {
                return v !== "id"
            })[0]].push(JSON.parse(j)) : null;
            return this
        }.bind(data);
        // set `id` at `data` , 
        // add first item to `data.arrayname` 
        classData("01", "abc", "single", {"id":"01", "arrayname":"files"});
        // set data at `data`
        classData("02", "def", "married");
        classData("02", "ghi", "single");
        // read `classData`
        console.log(classData());

        var data = {};
        
        var classData = function (id, name, status, options) {
            if (options) {
                this.id = options.id;
                this[options.arrayname] = [];
            };
            if (!this.hasOwnProperty("id")) {
                throw new Error("No id set on `classData` array."
                + "Please set `id` for `classData` at `options` object")
            };
            var j = (id && name && status) ? JSON.stringify({
                id: id,
                name: name,
                status: status
            }) : false;
            j ? this[Object.keys(this).filter(function (v) {
                return v !== "id"
            })[0]].push(JSON.parse(j)) : null;
            return this
        }.bind(data);
        // set `id` at `data` , 
        // add first item to `data.arrayname` 
        classData("01", "abc", "single", {"id":"01", "arrayname":"files"});
        // set data at `data`
        classData("02", "def", "married");
        classData("02", "ghi", "single");
        // read `classData`
        console.log(classData());

now i understand how can we check whether or not core data member will be check by using hasOwnProperty.

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