Definitions for the Lazy

This is bloody interesting (via Ajaxian). It involves creating functions at call time, where some expensive initial operation us computed and placed in a new function, which is then used to replace the original one.

For example,

function MyObject() {
    this.someFunction = function(x) {
        var a = someComplexCalculation();
        this.someFunction = function(y) {
            return a + y;
        };
        return this.someFunction(x);
    }
}

Pretty sweet.