Do you still use $ for jQuery? Well, don’t. If your code with $ resides with a SharePoint Images webpart, it will stop working. You’ll get errors like

Uncaught TypeError: Cannot call method 'empty' of null

The reason is that SharePoint uses $ in its own javascript code: CMSSiteManager.js

function $()
{ULSjlC:;
   var elements=new Array();
   for (var i=0; i < arguments.length; i++)
   {
	  var element=arguments\[i\];
	  if (typeof element=='string')
	  element=document.getElementById(element);
	  if (arguments.length==1) return element;
	  elements.push(element);
   }
   return elements;
}

I don’t know why, but (not always, just sometimes) IE doesn’t fire the onchange event (which is added as an attribute on an html element). A better “workaround” is to add an eventlistener in javascript. Or a lazy workaround is to use the onclick event even for checkboxes.

In my previous post I showed a little proof-of-concept for an httphandler which I want to use to dynamically get the localization resources from SharePoint as javascript object. But wait a moment. How does SharePoint handle localization on client? When you look in Script tab in Chrome dev tools, you’ll find:

ScriptResource.axd

It is added to the server when deployed. See a good introduction to WebResource.axd and ScriptResource.axd by Brian Chavez.

Sometimes I want to add some dynamic javascript code. E.g. I had an idea to get javascript code for localization dynamically. Kirk Evan provides a very clean approach to add ASP.NET HttpHandler to SharePoint. This is just a little lab: Create a SharePoint empty project. I call it Jerkelle. Create a class called Resx2JsHandler and implement the IHttpHandler interface Add the mapped folder Layouts and create Jerkelle.ashx file Here is the project. I probably will publish it on my github account: The Jerkelle.ashx file is very simple, it references to the code file (Resx2JsHandler.cs):

$.ajax is great, it hides much of the complexity. But sometimes we need to work with “raw” javascript :) So let’s look behind the scenes. The XMLHttpRequest (or just XHR) is used to open a connection to a server without a page reload. Internet Explorer calls it ActiveXObject and it differs in IE versions. Wikipedia article gives a good example how to create one constructor for all browsers:

if (typeof XMLHttpRequest == "undefined") XMLHttpRequest = function () {
  try {
    return new ActiveXObject("Msxml2.XMLHTTP.6.0");
  }
  catch (e) { }
  try {
    return new ActiveXObject("Msxml2.XMLHTTP.3.0");
  }
  catch (e) { }
  try {
    return new ActiveXObject("Microsoft.XMLHTTP");
  }
  catch (e) { }
  //Microsoft.XMLHTTP points to Msxml2.XMLHTTP and is redundant
  throw new Error("This browser does not support XMLHttpRequest.");
};

The remainder is more or less the same among the browsers. We open a connection defining the HTTP verb, URI and async mode (true or false):

When you load some data with ajax, you will probably want to show the users in some way, that data is loading. To show the text “loading…” would be enough. Another, very common way to do it to show a spinner, a rotating image. In sharepoint we can use the built-in gif which can be found in /_layouts/images/loading16.gif. Well, it is actually not so good, because this image is not so beautiful. A better way is to create your own gif image which is exactly suited for our needs. Or even better: don’t use any images. Use the light-weight javascript library called spin.js for creating spinners. It is fully customizable, compatible with older browsers. You can customize it interactively on the spin.js homepage.

String.trim() is quite useful in many situations. Unfortunately not all browsers have this function on String prototype (e.g. IE8): I see many people use jQuery.trim(), but isn’t it better to just use String.trim and provide a backup function if it is not implemented, like we did with Date.toISOString:

if(!String.prototype.trim) {
  String.prototype.trim = function() {
    return this.replace(/^\\s+|\\s+$/g, "");
  }
}
```EDIT: [found this solution on SO](http://stackoverflow.com/a/8522376/632117). Did we think the same?

In one of my previous posts I told about pushing a copy of an object into client. Now I’ll try to copy my resource values into client. The problem is often that we must create multiple localization resources: first as resx-file. If we use much ajax and client side rendering, we must provide some localization there, too. If they are different subsets of localization resources, it isn’t a problem. But when you get overlapping, it becomes more difficult to manage and sync them. See how Microsoft Ajax Library provides some strings: What if we just copy the values from resx file into client? If there are not business constraint it can make the development much easier. Let’s try it. For that we need Reflection. We start with changing the access modifiers on resx file to public: Then we must get all static properties of the auto-generated class (ResXFileCodeGenerator):

I have a simple html table, every row in tbody has a checkbox. thead has a checkbox. When it is checked/unchecked, all checkboxes have to be selected/ unselected. Here is a very simple javascript to achieve this:

$("#mytable thead :checkbox").live({
  change: function () {
    var checked = $(this).is(":checked");
    $("#mytable tbody :checkbox").attr("checked", checked);
  }
});

I have used jQuery tmpl for a while and it is really awesome. Now I want to use some nested templates. And the thing is: it is very simple to do it: Here is the code to achieve this:

<div onclick="doo()">test</div>
<div id="container"></div>
<script id="parent-template" type="text/html">
<li>
   {{tmpl t }}
</li>
</script>
<script id="red" type="text/html">
   <span style="color:red">{{= title}}</span>
</script>
<script id="green" type="text/html">
   <span style="color:green">{{= title}}</span>
</script>
<script type="text/javascript">
    var d = \[\];
    d.push({ title: "one", t: "red" });
    d.push({ title: "two", t: "green" });
    $.template("red", $("#red").template());
    $.template("green", $("#green").template());
    function doo() {
        $("#parent-template").tmpl(d).appendTo("#container");
    }
</script>