I got this request from Charlie:

Hi Alexander:
Is it possible to add a clickable “button” or icon next to a date picker that would insert “Today’s Date” into the field box?

Yes it is. Here’s a solution for setting either “first day of month”, “today” or “last day of month” by clicking on a link above the date picker, or by pressing “F”, “T” or “L” in the date picker field itself.

As always we start like this:
Create a document library to hold your scripts (or a folder on the root created in SharePoint Designer). In this example i have made a document library with a relative URL of “/test/English/Javascript” (a sub site named “test” with a sub site named “English” with a document library named “Javascript”):

The jQuery-library is found here. The pictures and the sourcecode refers to jquery-1.3.2.min. If you download another version, be sure to update the script reference in the sourcecode.

The code for the file “DateFieldValueOnClick.js” is found below.

Add a CEWP below – it is essential that it is placed below – your list-form as briefly described here, and add this code:

<script type="text/javascript" src="/Javascript/jquery-1.11.2.min.js"></script>
<script type="text/javascript" src="/Javascript/DateFieldValueOnClick.js"></script>
<script type="text/javascript">
	// Array of fields to add this function to
	var arrOfFields = ['MyDateColumn1','MyDateColumn2'];
	setDateFieldValue(arrOfFields);
</script>

The variable “arrOfFields” is an array of the FieldInternalNames of all the date picker-fields you want to add this feature to.

The code for the file “DateFieldValueOnClick.js” looks like this:

/* Set datepicker value to "first day of month", "today" or "last day if month"
 * ---------------------------------------------
 * Created by Alexander Bautz
 * alexander.bautz@gmail.com
 * https://spjsblog.com
 * v1.1
 * LastMod: 09.04.2014 
*/

function setDateFieldValue(arrOfFieldInternalNames){
if(typeof fields === 'undefined')fields = init_fields_v2();
// Get today's date
var today = new Date();
var m = today.getMonth()+1;
var d = today.getDate();
var y = today.getFullYear();
// Find last day in month
var lastDayRaw = new Date(y,m,0);
var dLast = lastDayRaw.getDate();

// Format your date
var T = m + "/" + d + "/" + y; // Today
var F = m + "/" + 1 + "/" + y; // First day in month
var L = m + "/" + dLast + "/" + y; // Last day in month
var fieldMouseoverTitle = "Press \"F\" for " + F + ", \"T\" for " + T + ", \"L\" for " + L;
$.each(arrOfFields,function(idx,item){
if(fields[item]==undefined)return;
$(fields[item]).find('input').attr('title',fieldMouseoverTitle).keyup(function(e){
if(e.keyCode==70){
setDate(item,F);
}
if(e.keyCode==84){
setDate(item,T);
}
if(e.keyCode==76){
setDate(item,L);
}
}).parents('td.ms-formbody:first').prepend("<div><span title='Set field value to \"" + F + "\"' style='cursor:pointer;' onclick=setDate(\"" + item + "\",\"" + F +"\")>First</span> | <span title='Set field value to \"" + T + "\"' style='cursor:pointer;' onclick=setDate(\"" + item + "\",\"" + T + "\")>Today</span> | <span title='Set field value to \"" + L + "\"' style='cursor:pointer;' onclick='setDate(\"" + item + "\",\"" + L +"\")'>Last</span></div>");
});
}

function setDate(fieldName,date){
	$(fields[fieldName]).find('input').val(date);
}

function init_fields_v2(){
	var res = {};
	$("td.ms-formbody").each(function(){
	var myMatch = $(this).html().match(/FieldName="(.+)"\s+FieldInternalName="(.+)"\s+FieldType="(.+)"\s+/);	
		if(myMatch!=null){
			// Display name
			var disp = myMatch[1];
			// FieldInternalName
			var fin = myMatch[2];
			// FieldType
			var type = myMatch[3];
			if(type=='SPFieldNote'){
				if($(this).find('script').length>0){
					type=type+"_HTML";
				}else if($(this).find("div[id$='TextField_inplacerte']").length>0){
					type=type+"_EHTML";
				}				
			}
			if(type==="SPFieldLookup"){
				if($(this).find("input").length>0){
					type=type+"_Input";
				}
			}
			// HTML Calc
			if(type==='SPFieldCalculated' && $(this).text().match(/(<([^>]+)>)/ig)!==null){
				$(this).html($(this).text());
			}		
			// Build object
			res[fin] = this.parentNode;
			$(res[fin]).attr('FieldDispName',disp);
			$(res[fin]).attr('FieldType',type);
		}		
	});
	return res;
}

Save this code as “DateFieldValueOnClick.js”, and upload to the script library as shown above.

Ask if something is unclear.

Regards
Alexander