Stack Implementation in JavaScript

function Stack() {
    this.reset();
}
 
Stack.prototype.pop = function () {
    if (this.empty() !== true) {
        this.length -= 1;
        return this.items.pop();
    }
    return undefined;
};
 
Stack.prototype.push = function (item) {
    this.items.push(item);
    this.length += 1;
    return true;
};
 
Stack.prototype.empty = function () {
    if (this.length === 0) {
        return true;
    }
    return false;
};
 
Stack.prototype.reset = function () {
    this.items = [];
    this.length = 0;
    return true;
};