all-events-today.js

// Function to pad month and day value
function pad(number) {
	var r = String(number);
	if (r.length === 1) {
		r = '0' + r;
	}
	return r;
}

var d = new Date();
// Construct ISO 8601 date strings by hand for the start and end of today
// these will be used in the caml query below
var todayStart = (d.getYear() + 1900) + '-' + pad((d.getMonth() + 1)) + '-' + pad(d.getDate()) + 'T00:00:00.000Z';
var todayEnd = (d.getYear() + 1900) + '-' + pad((d.getMonth() + 1)) + '-' + pad(d.getDate()) + 'T23:59:59.999Z';

// Get recurring events that occur today: http://georgetowndctechie.blogspot.com.au/2013/08/sharepoint-caml-query-to-get-todays.html -- it's lit
// CAML Query had to be changed slightly to include non-recurring events today
var caml = 	'<View>' +
				'<Query>' +
					'<OrderBy>' +
						'<FieldRef Name="EventDate"/>' +
					'</OrderBy>' +
					'<Where>' +
						'<Or>' +
							'<And>' +
								'<DateRangesOverlap>' +
									'<FieldRef Name="EventDate"/>' +
									'<FieldRef Name="EndDate"/>' +
									'<FieldRef Name="RecurrenceID"/>' +
									'<Value Type="DateTime" IncludeTimeValue="False">' +
										'<Today/>' +
									'</Value>' +
								'</DateRangesOverlap>' +
								'<Lt>' +
									'<FieldRef Name="EventDate"/>' +
									'<Value Type="DateTime">' +
										'<Today/>' +
									'</Value>' +
								'</Lt>' +
							'</And>' +
							'<And>' +
								'<Geq>' +
									'<FieldRef Name="EventDate"/>' +
									'<Value Type="DateTime">' + todayStart + '</Value>' +
								'</Geq>' +
								'<Leq>' +
									'<FieldRef Name="EventDate"/>' +
									'<Value Type="DateTime">' + todayEnd + '</Value>' +
								'</Leq>' +
							'</And>' +
						'</Or>' +
					'</Where>' +
					'<QueryOptions>' +
						'<IncludeMandatoryColumns>false</IncludeMandatoryColumns>' +
						'<ViewAttributes Scope="Recursive"/>' +
						'<RecurrencePatternXMLVersion>v3</RecurrencePatternXMLVersion>' +
						'<ExpandRecurrence>true</ExpandRecurrence>' +
						'<RecurrenceOrderBy>true</RecurrenceOrderBy>' +
						'<ViewAttributes Scope="RecursiveAll"/>' +
						'<CalendarDate>' +
							'<Today/>' +
						'</CalendarDate>' +
					'</QueryOptions>' +
				'</Query>' +
			'</View>';

var endpoint = _spPageContextInfo.siteAbsoluteUrl + "/_api/web/lists/GetByTitle('Example Calendar')/GetItems";
var requestData = JSON.stringify({
	"query": {
		"__metadata": {
			"type": "SP.CamlQuery"
		},
		"ViewXml": caml
	}
});

// Request form context. The reason for this being required is still a mystery!
// Without this code, the query against the Calendar will fail saying the form
// digest is invalid.
$.ajax({
	url: _spPageContextInfo.webAbsoluteUrl + "/_api/contextinfo",
	method: "POST",
	headers: {
		"Accept": "application/json; odata=verbose"
	}
})
	.then(function (contextInfo) {
		var request = $.ajax({
			url: endpoint,
			method: "POST",
			data: requestData,
			headers: {
				"X-RequestDigest": contextInfo.d.GetContextWebInformation.FormDigestValue,
				"Accept": "application/json; odata=verbose",
				"Content-Type": "application/json; odata=verbose"
			}
		})

		// Done and Fail handlers here...
	});