Question

Specifically, how can I write prototypes that allow chaining, such as the following:

$('myDiv').html('Hello World').fadeIn('slow');

Answer 1

Just return the appropriate stuff from the functions. The basic rule of thumb is take any method that would normaly return nothing and make it return this instead.

function Constructor(){};

Constructor.prototype = {
    foo: function(){
        console.log('foo');
        return this;
    },
    bar: function(x){
        console.log('bar', x);
        return this;
    }
}

var obj = new Constructor();
obj.foo().bar(17).bar(42).foo();