JSFiddle - React, Tailwind, and code Playground

JavaScript

var nm = getAndIncrementLastNumber("foo_0_bar_19");
alert(nm);

function getAndIncrementLastNumber(str){
   var myRe = /\d+[0-9]{0}$/g;  
   var myArray = myRe.exec(str);
   return parseInt(myArray[0])+1;
}