First pass at an Omnifocus Automation task that takes a selection of tasks from the clipboard, formats them for NotePlan tasks, and sends them to the note for the date selected.

noteplantasks.omnijs

/*{
    "author": "Michael Bishop",
    "targets": ["omnifocus"],
    "type": "action",
    "identifier": "com.miklb.NotePlan Tasks",
    "version": "0.2",
    "description": "A plug-in that takes a selection of tasks and formats them for NotePlan, appending them to the current days note.",
    "label": "NotePlan Tasks",
    "mediumLabel": "NotePlan Tasks",
    "paletteLabel": "NotePlan Tasks",
}*/
(() => {
    var action = new PlugIn.Action(function(selection) {
        if (Pasteboard.general.hasStrings) {
    Pasteboard.general.string = (
        Pasteboard.general.string
        .split('\n')
        .map(
            p => 0 < p.length ? (
                '- [ ] ' + p
            ) : p
        )
        .join('\n')
    );
    var noteBody = Pasteboard.general.string;
    var noteBody = encodeURIComponent(noteBody);

    var locale = "en-us"
var monthNames = []
for (i = 0; i < 12; i++) {
	var objDate = new Date()
	objDate.setDate(1)
	objDate.setMonth(i)
	monthName = objDate.toLocaleString(locale,{month:"long"})
	monthNames.push(monthName)
}

var now = new Date()
var currentYear = now.getFullYear()
var yearNames = new Array()
var yearIndexes = new Array()
for (i = 0; i < 4; i++) {
	yearNames.push(String(currentYear + i))
	yearIndexes.push(i)
}

var dayCount = new Date(currentYear, 1, 0).getDate()
var dayIndexes = new Array()
var dayIndexStrings = new Array()
for (var i = 0; i < dayCount; i++){
	dayIndexes.push(i)
	dayIndexStrings.push(String(i + 1))
}

var inputForm = new Form()

var yearMenu = new Form.Field.Option(
	"yearMenu",
	"Year",
	yearIndexes,
	yearNames,
	0
)

var currentYearIndex = 0


var monthMenu = new Form.Field.Option(
	"monthMenu",
	"Month",
	[0,1,2,3,4,5,6,7,8,9,10,11],
	monthNames,
	0
)

var currentMonthIndex = 0

var dayMenu = new Form.Field.Option(
	"dayMenu",
	"Day",
	dayIndexes,
	dayIndexStrings,
	0
)

inputForm.addField(yearMenu)
inputForm.addField(monthMenu)
inputForm.addField(dayMenu)
var formPrompt = "Select the date:"
var buttonTitle = "OK"
var formPromise = inputForm.show(formPrompt, buttonTitle)

inputForm.validate = function(formObject){
	var yearMenuIndex = formObject.values["yearMenu"]
	var chosenYear = parseInt(yearNames[yearMenuIndex])
	var monthMenuIndex = formObject.values["monthMenu"]
	
	if(monthMenuIndex != currentMonthIndex || yearMenuIndex != currentYearIndex){
		inputForm.removeField(inputForm.fields[2])
		currentMonthIndex = monthMenuIndex
		currentYearIndex = yearMenuIndex
	}

	if (formObject.fields.length == 2){
	
		var dayCount = new Date(chosenYear, monthMenuIndex + 1, 0).getDate()
	
		var dayIndexes = new Array()
		var dayIndexStrings = new Array()
		for (var i = 0; i < dayCount; i++){
			dayIndexes.push(i)
			dayIndexStrings.push(String(i + 1))
		}
	
		var dayMenu = new Form.Field.Option(
			"dayMenu",
			"Day",
			dayIndexes,
			dayIndexStrings,
			0
		)
	
		inputForm.addField(dayMenu)
	}

	return true
}


formPromise.then(function(formObject){
	var yearMenuIndex = formObject.values["yearMenu"]
	var yearName = yearNames[yearMenuIndex]
	var monthMenuIndex = formObject.values["monthMenu"]
	var monthName = monthNames[monthMenuIndex]
	var dayMenuIndex = formObject.values["dayMenu"]
	var dayIndexString = dayIndexStrings[dayMenuIndex]
    var targetDate = new Date(monthName + " " + dayIndexString + " " + yearName)
    var formateDate = Formatter.Date.withFormat("yyyyMMdd")
    var noteplanDate = f.stringFromDate(targetDate)
    console.log(noteplanDate);
    console.log(noteBody);
    URL.fromString('noteplan://x-callback-url/addText?noteDate=' + noteplanDate + '&text=' + noteBody + '&mode=append').open();
})

formPromise.catch(function(error){
	console.log("form cancelled", error.message)
})


}
    });

    // If needed, uncomment, and add a function that returns true if the current selection is appropriate for the action.
    /*
    action.validate = function(selection){

    };
    */
        
    return action;
})();