adding to associative array dynamically Javascript

Question

I am trying to dynamically add a key to my associative array. Instead of getting a dynamic 'key', I am getting literally 'elem' string instead of the string it contains. Please can someone advise?

For example I am getting in the console:

arrayOfSearchParams: [{"elem":["Active"]},{"elem":["Live:Studio","Test Unit"]},{"elem":["Les Copeland"]}]

My code

// Iterate through set. 
// Generate array of searchField and corresponding array of paramaters
var arrayOfSearchParams= [];
for(let elem of mySet){
    console.log('elem: ' + elem);

    var arrayParamters = [];

    for(var i=0; i < classArray.length; i++){
        if(classArray[i].checked == true){
            var field = classArray[i].getAttribute('data-table');
            if(elem == field){
                var param = classArray[i].getAttribute('value');
                arrayParamters.push(param);
            }
        }
    }

    arrayOfSearchParams.push({elem: arrayParamters});
}

console.log('arrayOfSearchParams: ' + JSON.stringify(arrayOfSearchParams));