データ構造-スタック

var Stack = function() {
    this.data = [];
};

Stack.prototype.print = function() {
    return this.data.join(',');
};

Stack.prototype.push = function(element) {
    this.data.push(element);
};

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

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

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

module.exports = Stack;

//   
var Stack = new Stack();