Question

Is it possible to swap a reference of an object that an array element contains to another index and remove/delete the old index.

Example:
I have an array of OBJECTS with indexes A, B, C, D.

Now I want to create a new array element with index F and assign it the reference of an object that index B contains. After that, I want to remove B from the array so that only A, C, D, E remains.

What I basically want to do is copy the reference of an object that index B contains and copy it to E.

I have tried the code below but it doesn’t work:

this.cache['A'] = new Orange(1);
this.cache['B'] = new Orange(2);
this.cache['C'] = new Orange(3);
this.cache['D'] = new Orange(4);

// I want to pass the reference B contains
// and assign it to F (like something you can do in C++)
this.cache['E'] = this.cache['B'];  

// First attempt
// length of array is 5 (cache['B'] just has value of undefined)
delete this.cache['B'];

// Second attempt
// the reference to object Orange was deleted in both B and E
this.cache.splice('B', 1);

I don’t want to create a new object and reassign the values, because there are many references and bindings to the objects, so doing a deep copy would be meaningless.

Answer 1

I’m wondering why the “splice” method is not the solution.

Look at my sample code. I’m using splice there and no any references is lost…

function Oo(s) {
    this._s = s;
}

Oo.prototype.toString = function() {
    return "-" + this._s+"-";
}

var a = [];
a.push(new Oo('x'));
a.push(new Oo('y'));
a.push(new Oo('z'));

a[3] = a[1];
alert(a);  // -x-,-y-,-z-,-y-

a[3]._s = 'XX'; // let's change the newly added item
alert(a); // -x-,-XX-,-z-,-XX- <- 3 and 1 points to the same object!

a.splice(1, 1); // remove one element, starting from index = 1
alert(a); // -x-,-z-,-XX-