LINQ-esque javascript array estentions

linq.js

Array.prototype.where = function (condition) {
    return this.filter(condition);
};
Array.prototype.select = function (attributes) {
    return this.map(attributes);
};
Array.prototype.sum = function () {
    return this.reduce((a, b) => a + b, 0);
};
Array.prototype.average = function () {
    return this.sum() / this.length;
};
Array.prototype.any = function (condition) {
    if (condition === undefined) {
        return this.length > 0;
    }
    return this.filter(condition).length > 0;
};
Array.prototype.first = function() {
    return this[0];
};
Array.prototype.not = function(object) {
    return this.filter((thing) => { return thing != object });
};
Array.prototype.take = function(count) {
    return this.slice(0, count);
};
Array.prototype.unique = function() {
    return this.sort().filter(function(value, index, array) {
        return (index === 0) || (value !== array[index - 1]);
    });
};
Array.prototype.skip = function(count) {
    return this.slice(count, this.length);
};
Array.prototype.copy = function () {
    return this.slice(0);
}
Array.prototype.max = function () {
    return Math.max.apply(Math, this);
}
Array.prototype.min = function () {
    return Math.min.apply(Math, this);
}