Question

    this.init = function (onupgradeneeded, onsuccess) {

        var openRequest = indexedDB.open(dbName);

        openRequest.onupgradeneeded = function (e) {

            db = e.target.result;

            if (!db.objectStoreNames.contains(objectStoreName)) {

                console.log('Creating the ' + objectStoreName + ' objectstore');

                db.createObjectStore(objectStoreName, { keyPath: "id", autoIncrement: true });

            }

        };

        openRequest.onsuccess = function (e) {

            db = e.target.result;

            db.onerror = function (event) {
                // Generic error handler for all errors targeted at this database requests
                console.log("Database error: " + event.target.errorCode);
            };
        };

    };

被叫：

var idb = new Demo.IndexedDB();
idb.init();

当init函数运行时，它将以openRequest.onupgradeneeded或openRequest.onsuccess结束。

我想知道的是，是否可以创建一个在两个函数中都被调用的泛型回调函数。因此无论运行的两个函数中的哪一个，我都可以通过使用

知道它们何时完成

idb.init(function(){
    //onupgradeneeded or onsuccess completed
});

希望你能得到这个想法，否则就会很复杂。

由于

Answer 1

只需传入一个回调函数，并在两种情况下调用一个回调函数：

this.init = function (onFinish) {

    var openRequest = indexedDB.open(dbName);

    openRequest.onupgradeneeded = function (e) {

        db = e.target.result;

        if (!db.objectStoreNames.contains(objectStoreName)) {

            console.log('Creating the ' + objectStoreName + ' objectstore');

            db.createObjectStore(objectStoreName, { keyPath: "id", autoIncrement: true });

        }
        onFinish();

    };

    openRequest.onsuccess = function (e) {

        db = e.target.result;

        db.onerror = function (event) {
            // Generic error handler for all errors targeted at this database requests
            console.log("Database error: " + event.target.errorCode);
        };
        onFinish();
    };

};

通用异步回调函数

1 个答案: