Useful JavaScript Methods

I am reading the book JavaScript: The Good Parts, and there are some code I found very useful, such as the sorting method for array.
The following is an example to short multiple keys in an array which containing both numbers and string.

// Function by takes a member name string and an
// optional minor comparison function and returns
// a comparison function that can be used to sort an
// array of objects that contain that member. The
// minor comparison function is used to break ties
// when the o[name] and p[name] are equal.

var by = function (name, minor) {
    return function (o, p) {
        var a, b;
        if (o && p && typeof o === 'object' && typeof p === 'object') {
            a = o[name];
            b = p[name];
            if (a === b) {
                return typeof minor === 'function' ? minor(o, p) : 0;
            }
            if (typeof a === typeof b) {
                return a < b ? -1 : 1;
            }
            return typeof a < typeof b ? −1 : 1;
        } else {
            throw {
                name: 'Error',
                message: 'Expected an object when sorting by ' + name;
            };
        }
    };
};

//Here is an example to sort by last name then first name:

var s = [
    {first: 'Joe',   last: 'Besser'},
    {first: 'Moe',   last: 'Howard'},
    {first: 'Joe',   last: 'DeRita'},
    {first: 'Shemp', last: 'Howard'},
    {first: 'Larry', last: 'Fine'},
    {first: 'Curly', last: 'Howard'}
];

s.sort(by('last', by('first')));    

// s is [
//    {first: 'Joe',   last: 'Besser'},
//    {first: 'Joe',   last: 'DeRita'},
//    {first: 'Larry', last: 'Fine'},
//    {first: 'Curly', last: 'Howard'},
//    {first: 'Moe',   last: 'Howard'},
//    {first: 'Shemp', last: 'Howard'}
// ]

Another example is the "bind" function.

Function.method('bind', function (that) {

// Return a function that will call this function as
// though it is a method of that object.

    var method = this,
        slice = Array.prototype.slice,
        args = slice.apply(arguments, [1]);
    return function (  ) {
        return method.apply(that,
            args.concat(slice.apply(arguments, [0])));
    };
});

//We can now bind the value to the x function.

var x = function (  ) {
    return this.value;
}.bind({value: 666});
console.log(x(  )); // 666