Convert to time in seconds (javascript)

convertToSeconds.js

var convertToSeconds = function(time) {
    
    if(!isNaN(time)){
        return time 
    }
    
    var timeArray = time.split(':'),
        seconds = 0, minutes = 1;

    while (timeArray.length > 0) {
        seconds += minutes * parseInt(timeArray.pop(), 10);
        minutes *= 60;
    }

    return seconds;

}