Question

I am seeing lots and lots of functions for reading cookies in via java script, but I only want to use it once and inside a variable, I am new to JS.

Here is my code

var TheNumber = (Math.random() + '') * 1000000000000000000;
document.cookie= "rand=" + TheNumber.toString() + ";path=/";
var AdServer = {
    tile: 1,
    mock: false,
    ord: (Math.random() + "") * 1000000000000000000 + '?',

I want to replace the ord part with the value from the rand cookie.

Could you guide me on the following:
Do I need a function?
If so where do I put it?
How would I call it?

Answer 1

I find the easiest (and most flexible) way to write/read from cookies with JavaScript is with global object with getter/setter methods.

The Mozilla dev docs page on document.cookie has a well documented example: https://developer.mozilla.org/en/DOM/document.cookie

How/where you might instantiate and then reference that object depends on the rest of your program, but assuming for simplicity we’re just in the global namespace and aren’t worried about variable collision etc:

var docCookies = {
    getItem: function (sKey) {  
      if (!sKey || !this.hasItem(sKey)) { return null; }  
      return unescape(document.cookie.replace(new RegExp("(?:^|.*;\\s*)" + escape(sKey).replace(/[\-\.\+\*]/g, "\\$&") + "\\s*\\=\\s*((?:[^;](?!;))*[^;]?).*"), "$1")); 
    },
    setItem: function (sKey, sValue, vEnd, sPath, sDomain, bSecure) {  
      if (!sKey || /^(?:expires|max\-age|path|domain|secure)$/.test(sKey)) { return; }  
      var sExpires = "";  
      if (vEnd) {  
        switch (typeof vEnd) {  
          case "number": sExpires = "; max-age=" + vEnd; break;  
          case "string": sExpires = "; expires=" + vEnd; break;  
          case "object": if (vEnd.hasOwnProperty("toGMTString")) { sExpires = "; expires=" + vEnd.toGMTString();  } break;  
        }  
      }  
      document.cookie = escape(sKey) + "=" + escape(sValue) + sExpires + (sDomain ? "; domain=" + sDomain : "") + (sPath ? "; path=" + sPath : "") + (bSecure ? "; secure" : "");  
    },
  hasItem: function (sKey) { return (new RegExp("(?:^|;\\s*)" + escape(sKey).replace(/[\-\.\+\*]/g, "\\$&") + "\\s*\\=")).test(document.cookie); }  
}

Then set your cookie with:

docCookies.setItem('rand', (Math.random()* 1000000000000000000).toString());

And get it with:

docCookies.getItem('rand');

So to put it all together:

var docCookies = {
    getItem: function (sKey) {  
      if (!sKey || !this.hasItem(sKey)) { return null; }  
      return unescape(document.cookie.replace(new RegExp("(?:^|.*;\\s*)" + escape(sKey).replace(/[\-\.\+\*]/g, "\\$&") + "\\s*\\=\\s*((?:[^;](?!;))*[^;]?).*"), "$1")); 
    },
    setItem: function (sKey, sValue, vEnd, sPath, sDomain, bSecure) {  
      if (!sKey || /^(?:expires|max\-age|path|domain|secure)$/.test(sKey)) { return; }  
      var sExpires = "";  
      if (vEnd) {  
        switch (typeof vEnd) {  
          case "number": sExpires = "; max-age=" + vEnd; break;  
          case "string": sExpires = "; expires=" + vEnd; break;  
          case "object": if (vEnd.hasOwnProperty("toGMTString")) { sExpires = "; expires=" + vEnd.toGMTString();  } break;  
        }  
      }  
      document.cookie = escape(sKey) + "=" + escape(sValue) + sExpires + (sDomain ? "; domain=" + sDomain : "") + (sPath ? "; path=" + sPath : "") + (bSecure ? "; secure" : "");  
    },
  hasItem: function (sKey) { return (new RegExp("(?:^|;\\s*)" + escape(sKey).replace(/[\-\.\+\*]/g, "\\$&") + "\\s*\\=")).test(document.cookie); }  
}
//set our cookie
docCookies.setItem('rand', (Math.random()* 1000000000000000000).toString());

then later/elsewhere in your code when you want to retrieve the cookie value:

var AdServer = {
    tile: 1,
    mock: false,
    ord: docCookies.getItem('rand')
};

Now if you inspect AdSever.ord it will equal the random number from your rand cookie that you set earlier.

console.log(AdServer.ord);