Gets the host application name

getHost.js

var current;
app.hostTypes = { Word :"Word", PowerPoint :"PowerPoint", Excel :"Excel"};
app.getHost = function () {
	if (current == null) {
		if (Office.context.requirements.isSetSupported('WordApi')) {
			current = app.hostTypes.Word;
		} else if (Office.context.requirements.isSetSupported('ExcelApi')) {
			current = app.hostTypes.Excel;
		} else {
			var host = $.urlParam("_host_Info");
			if (host.toLowerCase().indexOf("word",0) >= 0) {
				current = app.hostTypes.Word;
			} else if (host.toLowerCase().indexOf("excel",0) >= 0) {
				current = app.hostTypes.Excel;
			} else {
				current = app.hostTypes.PowerPoint;
			}
		}
		return current;
	}
	else {
		return current;
	}
};