https://www.uspsdelivers.com/wp-content/themes/uspsdelivers/js/lib/viewport.js

1"use strict"
2
3{
4  const init = function() {
5    if(!document || !document.documentElement) requestAnimationFrame(init)
6
7    const viewportRanges = [{
8      "id": "xs",
9      "min": 0,
10      "max": 599
11    },
12    {
13      "id": "sm",
14      "min": 600,
15      "max": 959
16    },
17    {
18      "id": "md",
19      "min": 960,
20      "max": 1279
21    },
22    {
23      "id": "lg",
24      "min": 1280,
25      "max": 1919
26    },
27    {
28      "id": "xl",
29      "min": 1920
30    }]
31    
32    const setRangeClasses = function(event) {
33      viewportRanges.forEach(function(range) {
34        if((!range.min || (range.min && window.innerWidth >= range.min)) && (!range.max || (range.max && window.innerWidth <= range.max))) {
35          document.documentElement.classList.add("usps-document--viewport-" + range.id)
36          document.documentElement.viewportRange = range.id
37        }
38
39        else {
40          document.documentElement.classList.remove("usps-document--viewport-" + range.id)
41        }
42      })
43    }
44
45    setRangeClasses()
46
47    window.addEventListener("resize", setRangeClasses)
48  }
49
50  init()
51}