JSFiddle - React, Tailwind, and code Playground

JavaScript

var s = "site.com/page_2/";
var x = s.split("/");
for(var i = 0; i < x.length; i++) {
    if(i==x.length-2) {
        var c = x[i].match(/page_(\d+)/)[1];
        alert(c);
    }
}