twitterCount.js

var text = "ハムマンのマンマンをハムハムしたいおっお(＾ω＾)❤";

console.log(twitterCount(text)); // 25

function twitterCount(text) {
	return [...text]
		.map((s)=> s.codePointAt())
		.map((c)=> {
			switch(true){
				case (c <= 0x10ff):
				case (c >= 0x2000 && c <= 0x200d):
				case (c >= 0x2010 && c <= 0x201f):
				case (c >= 0x2032 && c <= 0x2037):
					return 0.5;
				default:
					return 1;
			}
		})
		.reduce((a,b)=> a+b, 0) + 0.5 | 0;
}