JSFiddle - React, Tailwind, and code Playground
JavaScript
console.log(("str1,str2,str3,str4,str4,str4,str4,str4,str4,str4,str4".match(/,/g) || []).length); //logs 3
console.log(("str1,str2,str3,str4".match(new RegExp("str", "g")) || []).length); //logs 4