map-constructor-adder.js   [plain text]

// Map constructor with adder change.

var originalAdder = Map.prototype.set;
var counter = 0;

Map.prototype.set = function (key, value) {
    counter++;
    return originalAdder.call(this, key, value);
};

var values = [
    [ 0, 0 ],
    [ 1, 1 ],
    [ 2, 2 ],
    [ 3, 3 ],
    [ 4, 4 ],
    [ 5, 5 ],
    [ 4, 4 ],
    [ 3, 3 ],
    [ 2, 2 ],
    [ 1, 1 ],
    [ 0, 0 ],
];
var map = new Map(values);
if (map.size !== 6)
    throw "Error: bad map size " + map.size;
if (counter !== values.length)
    throw "Error: bad counter " + counter;

Map.prototype.set = function () {
    throw new Error("adder called");
};

var map = new Map();
var map = new Map([]);
var error = null;
try {
    var map = new Map([ [0, 0] ]);
} catch (e) {
    error = e;
}
if (!error)
    throw "Error: error not thrown";
if (String(error) !== "Error: adder called")
    throw "Error: bad error " + String(error);