var base_sku = "WST";

var sku_order = [{
  "char": "_",
  "terms": [
    {
      "parent": 14,
      "children": [
        {"id": 15, "sku_part": "4"},
        {"id": 16, "sku_part": "6"},
        {"id": 17, "sku_part": "8"},
        {"id": 30, "sku_part": "5"},
        {"id": 73, "sku_part": "42"}
      ]
    },
    {
      "parent": 10,
      "children": [
        {"id": 11, "sku_part": "CED"},
        {"id": 12, "sku_part": "GRA"},
        {"id": 13, "sku_part": "GRE"},
        {"id": 32, "sku_part": "BLA"},
        {"id": 33, "sku_part": "BLU"},
        {"id": 34, "sku_part": "BRO"},
        {"id": 35, "sku_part": "RED"},
        {"id": 36, "sku_part": "WHI"},
        {"id": 66, "sku_part": "BLUWHI"},
        {"id": 67, "sku_part": "CEDGRE"},
        {"id": 70, "sku_part": "RDW"},
        {"id": 130, "sku_part": "BROBLA"},
        {"id": 131, "sku_part": "CEDBLA"},
        {"id": 132, "sku_part": "GRABLA"}
      ]
    }
  ]
}],
option_list = [];

document.addEventListener("change", function () {
    let skuField = document.querySelector('[name="sku"], #sku');
    
    if (skuField && skuField.value && !skuField.value.includes("WST")) {
        skuField.value = "WST_" + skuField.value;
    }
});