We are developing a homepage with a few script web parts. Each web part has a reference to its own JavaScript. The web parts retrieve information from different SPLists. My web parts are somehow interferring with each other. If i remove the first one, the second works and vice versa. The code for each web part is similar to this:

$(document).ready(function () {
    SP.SOD.executeFunc('sp.js', 'SP.ClientContext', getSomeInfo);
});

function getSomeInfo() {
	var context = new SP.ClientContext.get_current();
	var oList = context.get_web().get_lists().getByTitle('MyList');
	var camlQuery = new SP.CamlQuery();
		
	camlQuery.set_viewXml('<View><Query><Where></Where></Query><ViewFields><FieldRef Name="Title" /><FieldRef Name="Link" /><FieldRef Name="Category" /></ViewFields></View>');
	this.collListItem = oList.getItems(camlQuery);
	context.load(this.collListItem, 'Include(Title, Link, Category)'); 
  		
	context.executeQueryAsync(Function.createDelegate(this, this.someInfoSucceeded), Function.createDelegate(this, this.someInfoFailed));               
}

function someInfoSucceded(sender, args) {
	var listItemEnumerator = collListItem.getEnumerator();
	while (listItemEnumerator.moveNext()) {
		var oListItem = listItemEnumerator.get_current();
		
		var title = oListItem.get_item('Title'); // This always works
		var linkDescription = oListItem.get_item('Link').get_description(); // Returns error
		var linkUrl = oListItem.get_item('Link').get_url(); // Returns error
		var category = oListItem.get_item('Category'); // Returns error
		
		// Code here to handle list item information...
	}
}

During the iteration I always get the title value, probably because it's an internal field. Every try to get the value of a custom field gives the following error:

The property or field has not been initialized. It has not been requested or the request has not been executed. It may need to be explicitly requested.

Remember: Every web part works fine when it exists alone on a page. But when I put another one on that page, one will work and one not. This leads me to believe that it has something to do with the client context. Maybe I shouldn't try to load it for every web part? If that is the case, how can I make them share a context? Use the master page to load sp.js and sp.clientcontext?

Please help me out, because I'm getting more confused by the minute.

• Edited by Papageno Sweden Friday, September 11, 2015 4:27 PM

Thanks for a thorough explanation with a code example. You are absolutely right, it was the scoping of the collListItem variable that was causing the trouble. I have now rewritten a few web parts using your design and everything is working.

The "this" keyword is quite useful, but can be your enemy if you don't understand it completely. I guess that was the problem in my case.

Thanks for taking the time to explain this to me.

• Edited by Papageno Sweden 15 hours 1 minutes ago