Here are a few assorted tricks which may make writing plugins less tedious:

If you need the value of a GUI setting at several places in you plugin's code, consider assigning it to a variable in JS, and using that instead of fetching it again and again with getString()/getBoolean()/getList(). This is faster, more readable, and less typing all at the same time:

function calculate () {
	var narm = "";	// na.rm=FALSE is the default in all functions below
	if (getBoolean ("remove_nas")) {
		$narm = ", na.rm=TRUE";
	}
	// ...
	echo ("results$foo <- foo (x" + narm + ")\n");
	echo ("results$bar <- bar (x" + narm + ")\n");
	echo ("results$foobar <- foobar (x" + narm "\n");
	// ...
}
	

The simple helper function makeOption() can make it easier to omit parameters that are at their default value, in many cases:

function calculate () {
	var options
	//...
	// This will do nothing, if VALUE is 0.95 (the default). Otherwise it will append ', conf.int=VALUE' to options.
	options += makeOption ("conf.int", getString ("confint"), "0.95");
	//...
}