save tag about array

@@ -14,20 +14,79 @@
   <h1><a href="main.html" color:black>KHU Chatting service</a></h1>
   <img src="image/signin.jpg" class="image">
 
+<!--refactoring and conditional statement -->
+
   <input id="night_day" type="button" value="night" onclick="
-  if(document.querySelector('body').style.backgroundColor==='black')
+  if(document.querySelector('#night_day').value==='night')
   {
-    document.querySelector('body').style.backgroundColor= 'white';
-    document.querySelector('body').style.color= 'black';
-    document.querySelector('#night_day').value= 'night';
+
+    var target=document.querySelector('body');
+
+    target.style.backgroundColor= 'black';
+    target.style.color= 'white';
+    document.querySelector('#night_day').value= 'day';
   }else{
+    target.style.backgroundColor= 'white';
+    target.style.color= 'black';
+    document.querySelector('#night_day').value= 'night';
+  }
+  ">
+<!-- about this grammer
+
+  <input type="button" value="night" onclick="
+  if(this.value==='night')
+  {
     document.querySelector('body').style.backgroundColor= 'black';
     document.querySelector('body').style.color= 'white';
-    document.querySelector('#night_day').value= 'day';
+    this.value= 'day';
+  }else{
+    document.querySelector('body').style.backgroundColor= 'white';
+    document.querySelector('body').style.color= 'black';
+    this.value= 'night';
   }
-
-
   ">
+ -->
+
+
+
+<!-- about array
+  <script>
+    var cowokers=["minsing","minsoft"];
+    document.write(cowokers[0]);
+    document.write(cowokers[1]);
+    cowokers.push("ssssss")
+    document.write(cowokers);
+  </script>
+-->
+
+<!-- about Loop
+<ul>
+  <script>
+  var i=0;
+    while(i<3)
+    {
+      document.write("<li>var</li>")
+      i+=1;
+    }
+  </script>
+</ul>
+-->
+
+
+
+<!--Loop & Array  -->
+<script>
+  var cowokers=["minsung","leezche","minsoft","sdy"];
+</script>
+
+<script>
+  var i=0;
+  while( i< cowokers.length ){
+    document.write('<li><a href="http://a.com/'+cowokers[i]+'">'+cowokers[i]+'</a></li>');
+    i+=1;
+  }
+</script>
+
 
   <div id="grid">
     <ol>