javascript：是否可以自动将对象推送到空数组（创建时）？

Question

is it possible that everytime an object is created (with a constructor i've built) it will be appended automatically to an empty array?

for example, i have a client constructor:

function client (firstName, lastName, id, code, balance) {
    this.firstName = firstName;
    this.lastName = lastName;
    this.id = id;
    this.code = code;
    this.balance = balance;
} 

and several instances:

var fred = new client("fred", "sou", 123456, 4545, 2500);
var george = new client("george", "potter", 852564, 5858, 1000);
var will = new client("will", "smith", 475896, 1234, 45000);

i am adding clients all the time, i don't want that everytime i register a client(creating an object) i would need to .push it to my array, like this:

var fred = new client("fred", "sou", 123456, 4545, 2500);
clientsArray.push(fred);
var george = new client("george", "potter", 852564, 5858, 1000);
clientsArray.push(george);
var will = new client("will", "smith", 475896, 1234, 45000);
clientsArray.push(will);

so, is there a way to define it automatically? i think that it is probably has something to do with the client constructor, but it's not an ordinary method (because again, i would have to call this method for every object i create).

anyone has an idea?

Answer 1

One way of doing this could be making the array prototype itself responsible for registering clients:

clientsArray.prototype.registerClient = function(firstName, lastName, id, code, balance){
    this.push(new client(firstName, lastName, id, code, balance))
};

After this, you could do:

clientsArray.registerClient("fred", "sou", 123456, 4545, 2500);

The other way around would be making the client register itself into the array (consider the responsibility - I don't think that that seems quite right). In real life, would a Client/patient register itself directly in the doctors database, or would the doctor(s assistant) be responsible for registering new clients? Most likely the latter (maybe they have to do some checks before the patient is added later on). Anyway, for that approach, just add:

function client (firstName, lastName, id, code, balance) {
    this.firstName = firstName;
    this.lastName = lastName;
    this.id = id;
    this.code = code;
    this.balance = balance;

    clientsArray.push(this);
} 

The example also assumes that there's only one "singleton" clientsArray. Else you could pass it as an argument. I think the first version is cleaner though.

Answer 2

var clientsArray = [];

function client (firstName, lastName, id, code, balance) {
    this.firstName = firstName;
    this.lastName = lastName;
    this.id = id;
    this.code = code;
    this.balance = balance;
    clientsArray.push(this);
} 

var fred = new client("fred", "sou", 123456, 4545, 2500);
var george = new client("george", "potter", 852564, 5858, 1000);
var will = new client("will", "smith", 475896, 1234, 45000);

Answer 3

Personally, I think it'd be the wrong approach to let another method wrap the construction of the object and even worse to bind it to a closure/global variable. What if you need just the client object and not to push into an array? Or what if your constructor parameters change? You'd have to modify both the method that wraps the constructor and the constructor to make it fit.

I think the approach you are following right now is the best approach, to inject the dependency like so.

clientsArray.push(new client("will", "smith", 475896, 1234, 45000));

But if you really must, you could just add an optional parameter:

function client (firstName, lastName, id, code, balance, clientsArr) {
    this.firstName = firstName;
    this.lastName = lastName;
    this.id = id;
    this.code = code;
    this.balance = balance;
    if(clientsArr) {
       clientsArr.push(this);
    }
}

And then:

var will = new client('will', 'smith', 475896, 1234, 45000, clientsArray);

If you don't need to push into an array:

var will = new client('will', 'smith', 475896, 1234, 45000);