function_genString.js

function generateStringByTemplate(arr){
	// FIXME: This is a temporary solution. It may cause overflows.
	// If you have an excellent way to do this, tell me.
	main = ""
	for (i of arr) { 
		z = ""
		if (typeof i != "string") { // is i not a string?
			if (Array.isArray(i))
				z = i // assign a placeholder
			else 
				throw new TypeError("indexed element is neither a string nor an array, got a(n) " + typeof i + "instead")

			while (Array.isArray(z)) { // if z is (still) a array, index to the end using a while loop (FIXME)
				z = z[Math.floor(Math.random() * z.length)] // get another (replacement) element
				if (typeof z != "string" && !Array.isArray(z)) // do it have a vaild type?
					throw new TypeError("randomly selected element in array z is neither a string nor an array, got a(n) " + typeof i + "instead")
			}
		}
		else
			z = i // just assign it to z
		main += z
	}
	return main
}

generateStringByTemplate([
	["Don't worry. ", ""],
	[["She","Her mom"],["He", "His dad"]], " ",
	["can", ["might", "may"], ["must", "have to"], "will"], " ",
	["call", ["call by phone to", "phone"]], " ",
	["you", "Jane", "John", ["Lily", "Lily's dad"]], "",
	[[" for it.", " for more info."], "."]
])