配列にfirst, lastメソッドを生やす ref: http://qiita.com/yuba/items/9b38fa15bc6b62e1ec71

file0.txt

/** Extends array object */
interface Array<T> {
    /** Returns the first element that satisfies the predicate */
    first(predicate:(element:T) => boolean, defaultVaule: T): T;
    /** Returns the last element that satisfies the predicate */
    last(predicate:(element:T) => boolean, defaultVaule: T): T;
}

Array.prototype.first = function (predicate: (element) => boolean, defaultVaule) {
    for (var i: number = 0; i < this.length; i++) {
        if (predicate(this[i])) return this[i];
    }
    return defaultVaule;
};
Array.prototype.last= function (predicate: (element) => boolean, defaultVaule) {
    for (var i: number = this.length; i-- > 0;) {
        if (predicate(this[i])) return this[i];
    }
    return defaultVaule;
};