construct-newtarget.js

Enable keyboard shortcuts

// |reftest| skip-if(!this.hasOwnProperty("Intl"))

// Test subclassing %Intl.PluralRules% works correctly.

class MyPluralRules extends Intl.PluralRules {}

var obj = new MyPluralRules();

assertEq(obj instanceof MyPluralRules, true);

assertEq(obj instanceof Intl.PluralRules, true);

assertEq(Object.getPrototypeOf(obj), MyPluralRules.prototype);

obj = Reflect.construct(MyPluralRules, []);

assertEq(obj instanceof MyPluralRules, true);

assertEq(obj instanceof Intl.PluralRules, true);

assertEq(Object.getPrototypeOf(obj), MyPluralRules.prototype);

obj = Reflect.construct(MyPluralRules, [], MyPluralRules);

assertEq(obj instanceof MyPluralRules, true);

assertEq(obj instanceof Intl.PluralRules, true);

assertEq(Object.getPrototypeOf(obj), MyPluralRules.prototype);

obj = Reflect.construct(MyPluralRules, [], Intl.PluralRules);

assertEq(obj instanceof MyPluralRules, false);

assertEq(obj instanceof Intl.PluralRules, true);

assertEq(Object.getPrototypeOf(obj), Intl.PluralRules.prototype);

// Set a different constructor as NewTarget.

obj = Reflect.construct(MyPluralRules, [], Array);

assertEq(obj instanceof MyPluralRules, false);

assertEq(obj instanceof Intl.PluralRules, false);

assertEq(obj instanceof Array, true);

assertEq(Object.getPrototypeOf(obj), Array.prototype);

obj = Reflect.construct(Intl.PluralRules, [], Array);

assertEq(obj instanceof Intl.PluralRules, false);

assertEq(obj instanceof Array, true);

assertEq(Object.getPrototypeOf(obj), Array.prototype);

// The prototype defaults to %PluralRulesPrototype% if null.

function NewTargetNullPrototype() {}

NewTargetNullPrototype.prototype = null;

obj = Reflect.construct(Intl.PluralRules, [], NewTargetNullPrototype);

assertEq(obj instanceof Intl.PluralRules, true);

assertEq(Object.getPrototypeOf(obj), Intl.PluralRules.prototype);

obj = Reflect.construct(MyPluralRules, [], NewTargetNullPrototype);

assertEq(obj instanceof MyPluralRules, false);

assertEq(obj instanceof Intl.PluralRules, true);

assertEq(Object.getPrototypeOf(obj), Intl.PluralRules.prototype);

// "prototype" property is retrieved exactly once.

var trapLog = [], getLog = [];

var ProxiedConstructor = new Proxy(Intl.PluralRules, new Proxy({

    get(target, propertyKey, receiver) {

        getLog.push(propertyKey);

        return Reflect.get(target, propertyKey, receiver);

}, {

    get(target, propertyKey, receiver) {

        trapLog.push(propertyKey);

        return Reflect.get(target, propertyKey, receiver);

}));

obj = Reflect.construct(Intl.PluralRules, [], ProxiedConstructor);

assertEqArray(trapLog, ["get"]);

assertEqArray(getLog, ["prototype"]);

assertEq(obj instanceof Intl.PluralRules, true);

assertEq(Object.getPrototypeOf(obj), Intl.PluralRules.prototype);

if (typeof reportCompare === "function")

    reportCompare(0, 0);