Javascript Data Structure Stack via backend array

function Stack(array) {
    this.array = [];//  ww w.j  a v a2 s  . c  o  m
    if (array) this.array = array;
}

Stack.prototype.getBuffer = function() {
    return this.array.slice();
}

Stack.prototype.isEmpty = function() {
    return this.array.length == 0;
}

Stack.prototype.peek = function() {
    return this.array[this.array.length - 1];
}


Stack.prototype.push = function(value) {
    this.array.push(value);
}


Stack.prototype.pop = function() {
    return this.array.pop();
};

//instance of the stack class
var stack1 = new Stack();

console.log(stack1); // {array: []}

stack1.push(1);
stack1.push(2);
stack1.push(3);
console.log(stack1); // {array: [1,2,3]}

stack1.pop(1);
stack1.pop(2);
stack1.pop(3);

console.log(stack1); // {array: []}
stack1.push(10);
console.log(stack1.peek()); // 10
stack1.push(5);
console.log(stack1.peek()); // 5