How to conduct lookup and alert Javascript object based on URL string

Question

I'm trying to figure out how to alert a JavaScript object based on the URL string. The URL will have a URL string that includes something like this: ?cat=2

I have the following object created:

var cat = (new URL(location)).searchParams.get('cat')

var CAT_LOOKUP = {
        1:   {
                category:  "Fire", 
                idAttr:    "fire", 
                name:      "fire"
             },
        2:   {
                category:  "Medical Staff", 
                idAttr:    "medicalStaff", 
                name:      "medicalStaff"
             },
        3:   {
                category:  "Physician", 
                idAttr:    "physician", 
                name:      "physician"
             },
        4:   {
                category:  "Police", 
                idAttr:    "police", 
                name:      "police"
             }
}

I have this started to display the alert, but am missing something:

function alertCat(obj){      
            for(var key in obj) {
            alert('key: ' + key + '\n' + 'value: ' + obj[key]);
            if( typeof obj[key] === 'object' ) {
                alertObject(obj[key]);
            }
            }
        }
alertCat(CAT_LOOKUP[cat]);

I need access to the object for use in a form on the page.

Answer 1

I figured it out:

    $( document ).ready(function() {
    var cat = (new URL(location)).searchParams.get('cat')
    alert('T = ' + cat);

    var CAT_LOOKUP = {
            1:   {
                    category:  "Fire", 
                    idAttr:    "fire", 
                    name:      "fire"
                 },
            2:   {
                    category:  "Medical Staff", 
                    idAttr:    "medicalStaff", 
                    name:      "medicalStaff"
                 },
            3:   {
                    category:  "Physician", 
                    idAttr:    "physician", 
                    name:      "physician"
                 },
            4:   {
                    category:  "Police", 
                    idAttr:    "police", 
                    name:      "police"
                 }
    }

    alert(CAT_LOOKUP[cat].category);

});