A while ago, I created a JavaScript library named Xccessors, which implemented the legacy non-standard accessor (getter and setter) methods in IE8. I initially created two different libraries and decided that the library that implemented the legacy methods would be more useful at the time due to no changes needed in a JavaScript program’s code to add accessor support for IE. I never released the second one that implements the ECMAScript 5 (formerly 3.1) standard accessor methods so I’m releasing it now. There can’t be two different libraries with the same “Xccessors” name, so I am also renaming the libraries accordingly to what they implement. The new names are Xccessors Legacy and Xccessors Standard.

Here are two examples of using Object.defineProperty and Object.getOwnPropertyDescriptor:

Using accessors

(function() {
// this creates a document.foo accessor
    var foo = 0;
    Object.defineProperty(document, "foo", {
        get: function() { return foo },
        set: function(x) { return foo += x }
    });
})();
 
document.foo = 5;
(document.foo = 4) === 9;
//Object.getOwnPropertyDescriptor(document, "foo") is {set:[...], get:[...]}

Setting a property

// this is the equivalent of window.foo = "bar";
Object.defineProperty(window, "foo", {value: "bar"});
window.foo === "bar";
Object.getOwnPropertyDescriptor(window, "foo").value === "bar";
window.x = 0;
Object.getOwnPropertyDescriptor(window, "x").value === 0;