cache property lookup.js

// So this will run in a browser as well as a shell.
if (this.window) {
    window.print = function(s) { console.log(s); }
}

var TOTAL = 1e5;
var row = 0;
var data = {
    rows: [{ a: "hi", b: 1, c: true, d: "wah!" }]
};

print('expected: ' + TOTAL*3);

// Test without caching property lookups
(function() {
    var start = Date.now();
    var count = 0;
    for (var i=0; i<TOTAL; ++i)
        for (var item in data['rows'][row])
            if (typeof data['rows'][row][item] === 'string' || typeof data['rows'][row][item] === 'number')
                count++;
    var end = Date.now();
    print('count: ' + count);
    print(end-start+'ms');
})();

// Test with caching property lookups
(function() {
    var start = Date.now();
    var count = 0;
    for (var i=0; i<TOTAL; ++i) {
        var theRow = data.rows[row];
        for (var itemName in theRow) {
            var item = theRow[itemName];
            if (typeof item === 'string' || typeof item === 'number')
                count++;
        }
    }
    var end = Date.now();
    print('count: ' + count);
    print(end-start+'ms');
})();