Step 1: Loading Shopping Bag

JavaScript and the resident browser take care of most of the work here, although the user plays a small part. Consider the first page loaded—index.html. You can see what it looks like in Example 8.1.

Example 8-1. index.html 

     1  <HTML>
     2  <HEAD>
     3  <TITLE>Shopping Bag</TITLE>
     4  <STYLE TYPE="text/css">
     5  <!--
     6  #welcome { text-align: center; margin-top: 150}
     7  //-->
     8  </STYLE>
     9  <SCRIPT LANGUAGE="JavaScript">
    10  <!--
    11  var shopWin = null;
    12  var positionStr = '';
    13  function whichBrowser() {
    14    if(navigator.appVersion < 4) { 
    15      alert("You need MSIE 4.x or Netscape Navigator 4.x to use " + 
    16        "Shopping Bag.")
    17      return false;
    18      }
    19    return true;
    20    }
    21  
    22  function launch() {
    23    if(!whichBrowser()) { return; }
    24    if(navigator.appName == "Netscape") 
    25      { positionStr = ",screenX=0,screenY=0"; }
    26    else { positionStr = ",fullscreen=yes"; }
    27    if(shopWin == null) {
    28      shopWin = open("shopset.html", "", "width=" + screen.width + 
    29        ",height=" + screen.height + positionStr);
    30      }
    31    }
    32  function closeUpShop() {
    33    if (shopWin != null) {
    34      if (typeof(shopWin) == "object") {
    35        shopWin.close();
    36        }
    37      }
    38    }
    39  window.onunload = closeUpShop;
    40  //-->
    41  </SCRIPT>
    42  </HEAD>
    43  <BODY>
    44  <DIV ID="welcome"> 
    45    <H1>Welcome to Shopping Bag!!!</H1>
    46    <A HREF="javascript: launch();">Begin</A>
    47  </DIV>
    48  </BODY>
    49  </HTML>

That might seem like a lot of JavaScript for a page that prints only five words on the screen; however, the additional code makes for a slightly ...

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