13. 상태 모드

// OffLightState：
var OffLightState = function(light) {
    this.light = light;
};

OffLightState.prototype.buttonWasPressed = function() {
    console.log('  '); // offLightState      
    this.light.setState(this.light.weakLightState); //      weakLightState
};
// WeakLightState：
var WeakLightState = function(light) {
    this.light = light;
};

WeakLightState.prototype.buttonWasPressed = function() {
    console.log('  '); // weakLightState      
    this.light.setState(this.light.strongLightState); //      strongLightState
};
// StrongLightState：
var StrongLightState = function(light) {
    this.light = light;
};

StrongLightState.prototype.buttonWasPressed = function() {
    console.log('  '); // strongLightState      
    this.light.setState(this.light.offLightState); //      offLightState
};

var Light = function() {
    this.offLightState = new OffLightState(this);
    this.weakLightState = new WeakLightState(this);
    this.strongLightState = new StrongLightState(this);
    this.button = null;
};

Light.prototype.init = function() {
    var button = document.createElement('button'),
        self = this;
    this.button = document.body.appendChild(button);
    this.button.innerHTML = '  ';
    this.currState = this.offLightState; //       
    this.button.onclick = function() {
        self.currState.buttonWasPressed();
    }
};

Light.prototype.setState = function(newState) {
    this.currState = newState;
};

var light = new Light();
light.init();