UpdateMap.js

**
 * Adding new functionality does not require modify "code"
 * We can simply update our map with new case converter
 */

function changeCase(word, caseType) {

    const caseMap = {
        "lower": convertToLower,
        "camel": convertToCamel,
        "proper": convertToProper
    }

    // Convert switch case to map(string, function)
    caseType = caseType.trim().toLowerCase();
    var conversion = caseMap[caseType];

    // Make sure we got the conversion function
    return conversion? caseMap[caseType](word) : null;
}