[JavaScript][Example] get mode from a list of numbers

This post mark down the logic using javaSrcipt get the modes, source samples are with string data type and separated by comma.

<script>
const ROUND_TO_FIXED = 2;
function _stringToList(string){
    return string.split(",");
}
function _roundToFixed(num){
    return Number(parseFloat(num).toFixed(ROUND_TO_FIXED));
}
function getSampleModes(string){
    var sourceList  = _stringToList(string);
    var max         = -Infinity, x;
    var json        = {},
        frequencies = {}
    var modes       = [];
    //Records the occurs of numbers
    for(var key in sourceList){
        if(! (sourceList[key] in frequencies)){
            frequencies[sourceList[key]] = 1;
        }else{
            frequencies[sourceList[key]] += 1;
        }
    }
    // Get modes
    for(var key in frequencies) {
       if( frequencies[key] > max) max = frequencies[key];
       if( frequencies[key] == max) modes.push(key);
    }
    return modes;
}
var source = "1,2,3,5,1,2,6"
console.log(getSampleModes(source));
</script>

Result

Refercene:
https://en.wikipedia.org/wiki/Mode_(statistics)