Unable to get property 'get_current' of undefined or null reference

Question

 $(document).ready(function () {
            var count = 0;

retrieveCurrentListProperties();


            function retrieveCurrentListProperties() {
                clientContext = new SP.ClientContext.get_current();
                web = clientContext.get_web();
                var list = web.get_lists().getByTitle("Urgent Alerts");
                var camlQuery = new SP.CamlQuery();
                var q =  "<View><Query><Where><Eq><FieldRef Name='End_x0020_Date'/><Value Type='DateTime'><Today/></Value></Eq></Where></Query></View>";
                camlQuery.set_viewXml(q);
                this.listItems = list.getItems(camlQuery);
                clientContext.load(this.listItems);
                clientContext.executeQueryAsync(Function.createDelegate(this, this.onCListItemsLoadSuccess), 
                Function.createDelegate(this, this.onQueryFailed));

            }

            function onCListItemsLoadSuccess(sender, args) {



                var listEnumerator = this.listItems.getEnumerator();
    //iterate though all of the items

                count = this.listItems.get_count();

alert(count);

            }
            function onQueryFailed(sender, args) {
                alert('request failed ' + args.get_message() + '\n' + args.get_stackTrace());
            }
 });

Here is my code I get an error Unable to get property 'get_current' of undefined or null reference is there anything I need to import to get this to work?

Answer 1

If this is an app or anything outside of a SharePoint page you need to load

document.write('<script src="' + spHostUrl + '/_layouts/15/MicrosoftAjax.js"><\/script>')
document.write('<script src="' + spHostUrl + '/_layouts/15/sp.runtime.js"><\/script>')
document.write('<script src="' + spHostUrl + '/_layouts/15/sp.js"><\/script>')

where hostUrl is the path to your SharePoint site (not the app web).

You should also use

SP.SOD.executeFunc('sp.js', null, function(){
      retrieveCurrentListProperties();
})

to make sure that sp.js is loaded before executing your function

Answer 2

[Applies to SP 2010]

You need to make sure that the SP.js file is loaded before executing the function.

Taken from the MSDN:

SP.SOD.execute

Executes the specified function in the specified file with the optional arguments.

SP.SOD.executeOrDelayUntilScriptLoaded

Executes the specified function after the file specified has been loaded; otherwise, adds it to the pending job queue.

In your case, you need to call the latter (executeOrDelayUntilScriptLoaded), as the function to be called is not contained within the SP.js file.

So your code should look like:

<script type="text/javascript">

ExecuteOrDelayUntilScriptLoaded(retrieveCurrentListProperties, "SP.js");
function retrieveCurrentListProperties() { // code omitted for brevity }
function onCListItemsLoadSuccess(sender, args) {}
function onQueryFailed(sender, args) {}

</script>

Answer 3

dont use new keyword for the instation of sharepoint javascript object.

the below declaration is the correct

SP.ClientContext.get_current();

Answer 4

This happens only when you refresh the opened page more than once. Try opening the record again newly and you will not see this issue.