Answers for "how to find out words starting with certain letter in javascript"

js startswith

var str = "Hello world, welcome to the universe.";
var n = str.startsWith("Hello");

javascript multiple startswith

//There is NO possibility to passing an Array
//like startsWith(["Mon" | "Tues"])
if (newStr4.startsWith("Mon") || newStr4.startsWith("Tues") || ...)

//although you can use regular expression,
//but performance are lower than the solution above
 if (newStr4.matches("(Mon|Tues|Wed|Thurs|Fri).*"))