perfPromiseThen.js

// results: new P, new P ~160ms
// results: new P, new PP ~190ms
// results: new PP, new PP ~210ms
function P() {

}


P.prototype.then = function (fn, arg) {
    fn();
};
var Then = P.prototype.then;
P.prototype.resolve = function (promise) {
    if (typeof promise === 'object' && promise !== null && typeof promise.then === 'function') {
        if (promise.then === Then) {
            promise.then(promise.next, promise);
        } else {
            this.bind(promise);
        }
    }
};

function bind(promise, _this) {
    promise.then(function () {
        _this.next();
    });
}

P.prototype.bind = function(promise) {
    var _this = this;
    promise.then(function () {
        _this.next();
    });
}


P.prototype.next = function () {

};

function PP() {

}

PP.prototype.then = function () {

};


function DD() {

}
var a = [
    1,
    null,
    void 0,
    "12",
    true,
    {},
    {x: 1},
    {y: 1},
    {z: 1},
    {m: 1},
    {o: 1},
    new DD(),
    // new P(),
    new P(),
    new PP(),
    // new PP(),
    // {then: 1},
    // {then: "1"},
    // {then: {}},
    /*{
        then: function () {
        }
    },
    {
        then: function () {
        }
    },*/
    // new P()
    0
];

var promise = new P();

function abc() {
    console.time('perf');
    for (var i = 0; i < 1000000; i++) {
        for (var j = 0; j < a.length; j++) {
            var x = a[j];
            promise.resolve(x);
        }
    }
    console.timeEnd('perf');

}

abc();