JSFiddle - React, Tailwind, and code Playground

HTML

<section id="questions-688"></section>
<section id="test"></section>
<section id="stats-688"></section>
<section id="answers-636"></section>
<section id="someDiv"></section>

JavaScript

var sections = document.querySelectorAll('section[id^=stats-],section[id^=answers-],section[id^=questions-]'),
segments = [];

for (var i = 0; i < sections.length; i++) {
    var split = sections[i].id.split('-');
    if (segments.indexOf(split[1]) == -1) {
        segments.push(split[1]);
    }    
}

alert(segments)