Simple functional refactoring

functional-reffactoring.js

// original code
function printTrace(log) {
    for (var i = 0; i < log.length; i++) {
        var entry = log[i];
        var args = entry.args;
        var argstring = "(";
        for (var j = 0; j < args.length - 1; j++) {
            argstring += args[j].toString() + ",";
        }
        if (args.length > 0) {
            argstring += args[args.length - 1].toString();
        }
        argstring += ")";
        console.log(log.id + ": " + entry.op + argstring + ' returned: ' + entry.result);
    }
}

// ...after replacing explicit loops with 'map'
function printTrace(log) {
    log.map(function(entry) {
      console.log(log.id + ": " + entry.op + '(' + entry.args + ')' + ' returned: ' + entry.result);
    });
}

// ...finally, using shorthand for anonymous functions -'fat arrow' from ES6
function printTrace(log) {
    log.map(entry => console.log(log.id + ": " + entry.op + '(' + entry.args + ')' + ' returned: ' + entry.result));
}