JSFiddle - React, Tailwind, and code Playground

HTML

<script src="http://defiantjs.com/defiant.js/dist/defiant-latest.min.js"></script>
Found <span id="count"></span> items.

JavaScript

var data = {
      "sizes": [
         {
            "L": "20/18",
            "M": "10/7",
            "S": "30/26",
            "2XL": "50/20",
            "color": "MIX"
         },
         {
            "L": "10/6",
            "M": "10/6",
            "S": "10/8",
            "2XL": "20/18",
            "color": "SR"
         },
         {
            "L": "10/7",
            "M": "30/26",
            "S": "50/20",
            "3XL": "10/6",
            "color": "MIX"
         },
         {
            "L": "10/6",
            "M": "10/8",
            "S": "20/18",
            "XL": "10/7",
            "color": "BL"
         },
         {
            "L": "30/26",
            "M": "50/20",
            "S": "10/6",
            "3XL": "10/6",
            "color": "FGN"
         }
      ]
   },
   found = JSON.search(data, '//*[@d:name="3XL"]');

document.getElementById('count').innerHTML = found.length;