CheckSPListDataType.js

/*
 Get a SharePoint List Metadata for Use in REST API code.
 
 1. Create a List and Add one item into it.
 2. Create a SitePage and Insert a Script Editor into it.
 3. Edit the WebPart to insert the code below inside.
 4. Save the File.
 5. Open Fiddler and inspect the Data from JSON tab.
 6. You are good.
*/



<div>
    <div id="message"></div>
</div>

<script
  src="https://code.jquery.com/jquery-2.2.4.min.js"
  integrity="sha256-BbhdlvQf/xTY9gja0Dq3HiwQF8LaCRTXxZKRutelT44="
  crossorigin="anonymous"></script>
<script type="text/javascript">
/* 
    Created on : Sep 6, 2017, 8:44:02 AM
    Author     : David Mutua
*/

var queryFirst = function () {
    var invokation = $.ajax({
        url : _spPageContextInfo.webAbsoluteUrl + "/_api/Web/Lists/GetByTitle('Demand')/Items",
        type: "GET",
        dataType: "json",
        headers: {
            Accept: "application/json;odata=verbose"
        }
    });
    
    invokation.done(function (data, textStatus, jqXHR) {
        var message = $("#message"); 
        message.text(data.d.results.length);
    });
    
    invokation.fail(function (jqXHR, textStatus, errorThrown) {
        var response = JSON.parse(jqXHR.responseText);
        var message = response ? response.error.message.value : textStatus;
        alert("Call failed on CreateItem() Error: "+ message);
    });
}();
</script>