Pushing, Popping, and Displaying the Contents of a Stack

Pushing, Popping, and Displaying the Contents of a Stack : Stack : Language Basics JAVASCRIPT DHTML TUTORIALS

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Pushing, Popping, and Displaying the Contents of a Stack



<HTML>
<HEAD>
<TITLE>Stacking up!</TITLE>
<SCRIPT> 
var stack = new Array(); 
function pushStack(newVal) { 
   stack.push(newVal); 
} 
function popStack() { 
   var popVal = stack.pop(); 
   if (popVal == undefined) 
      return "Empty stack!"; 
   else 
   return popVal; 
} 
function showStack(theSelect){ 
   theSelect.options.length = 0; 
   for (var i = 0; i < stack.length; i++){ 
      var theOption = new Option(stack[i]); 
      theSelect.options[theSelect.options.length] = theOption; 
   } 
} 
</SCRIPT>
</HEAD>
<BODY>
<FORM>
<INPUT type=text name=txtPush>
<INPUT type=button value="Push" onClick='pushStack(txtPush.value); txtPush.value=""; showStack(theList);'>
<SELECT name="theList" size=12>
<OPTION>Displays the current state of the stack! 
</SELECT>
<INPUT type=text name=txtPop size=25>
<INPUT type=button value="Pop" onClick="txtPop.value = popStack(); 
   showStack(theList);">
</FORM>
</BODY>
</HTML>