<script>
  var coworkers = {
    "programmer" : "james",
    "designer" : "tim"
  }
            
    document.write(coworkers.programmer);
    coworkers.pm = "curry";
    coworkers["data scientist"] = "westbrook"; // 띄어쓰기를 사용하고 싶을 때
    document.write(coworkers["data scientist"]);
</script>

<script>
    for(var key in coworkers){
        document.write(coworkers[key]+'<br>');
    }
</script>

 <script>
    coworkers.showAll = function(){
        for(var key in this){
        document.write(this[key]+'<br>');
        }
    }
</script>

<script>
    var Body = {
        setColor: function (color){
            var target = document.querySelector('body');
            target.style.color = color;
        },
        setBackColor : function (color){
            document.querySelector('body').style.backgroundColor = color;
        }
    }

    var Links = {
        setColor: function (color){
            var alist = document.querySelectorAll('a');
            var i = 0;
            while (i < alist.length){
                alist[i].style.color = color;
                i = i + 1; 
            }
        }
    }
  
    function nightDayHandler(self){
        // var target = document.querySelector('body');
        if(self.value === 'night'){
            Body.setBackColor('black');
            Body.setColor('white');
            self.value = 'day';

            Links.setColor('powderblue');
        } else{
            Body.setBackColor('white');
            Body.setColor('black');
            self.value = 'night';

            Links.setColor('blue');
        }
    }
    </script>