Jquery 每个循环完成前调用的函数

Question

下面是我的一个函数，它传递了一个 JSON 对象。我遍历 JSON 并使用在每个 JSON 元素中找到的信息更新本地数据库。问题是我的函数 "getAEDFromDB" 在每个循环完成之前被调用。我怎样才能确保它在我的循环结束后被调用？

function getAEDFromWeb_callBack(json) { 
        var hasUpdated = true;

        alert("getAEDfromWeb_callback" + JSON.stringify(json));

        $.each(JSON.parse(json), function(idx, obj) {
            //check if id exists
            db.transaction(function (t) {
                t.executeSql('SELECT * FROM tbAED WHERE id = ' + obj.id, null, function (t, data) {
                    if (data.rows.length > 0) {
                        //exists - therefore update
                        alert("update AED");
                        t.executeSql("UPDATE tbAED SET name='" + obj.name + "',address='" + obj.address + "',address2='" + obj.address2 + "',latitude='" + obj.latitude + "',longitude='" + obj.longitude + "',description='" + obj.description + "',photo='" + obj.picture + "',status=" + obj.status + " WHERE id=" + obj.id, [], function (t, data) {
                            hasUpdated = true;
                        },
                        function(t, e) {
                            alert('1 error table insert settings. ' + e.message);
                        });
                    } else { 
                        //doesnt exist therefore insert
                        alert("insert AED");
                        t.executeSql("INSERT INTO tbAED (id,name,address,address2,latitude,longitude,description,photo,status) VALUES (" + obj.id + ",'" + obj.name + "','" + obj.address + "','" + obj.address2 + "','" + obj.latitude + "','" + obj.longitude + "','" + obj.description + "','" + obj.picture + "'," + obj.status + ")", [], function (t, data) {
                            hasUpdated = true;
                        },
                        function(t, e) {
                            alert('2 error table insert settings. ' + e.message);
                        });
                    }
                },
                function(t, e) {
                    alert('error sql. ' + e.message);
                });
            });
        })

        alert("done");

        if (hasUpdated==true) {
            alert("update settings with date");
            db.transaction(function (t) {
                t.executeSql("UPDATE tbSettings SET lastupdate = '" + _templastupdate + "' WHERE userid = " + _userid + ";", [], function (t, data) {
                    _lastupdate = _templastupdate;
                },
                function(t, e) {
                    alert('error updating lastupdate settings. ' + e.message);
                });
            });
        }

        getAEDFromDB();
    }

谢谢

Answer 1

  db.transaction(function (t) {
      $.each(JSON.parse(json), function(idx, obj) {
        //check if id exists
            t.executeSql('SELECT * FROM tbAED WHERE id = ' + obj.id, null, function (t, data) {
                if (data.rows.length > 0) {
                    //exists - therefore update
                    alert("update AED");
                    t.executeSql("UPDATE tbAED SET name='" + obj.name + "',address='" + obj.address + "',address2='" + obj.address2 + "',latitude='" + obj.latitude + "',longitude='" + obj.longitude + "',description='" + obj.description + "',photo='" + obj.picture + "',status=" + obj.status + " WHERE id=" + obj.id, [], function (t, data) {
                        hasUpdated = true;
                    },
                    function(t, e) {
                        alert('1 error table insert settings. ' + e.message);
                    });
                } else { 
                    //doesnt exist therefore insert
                    alert("insert AED");
                    t.executeSql("INSERT INTO tbAED (id,name,address,address2,latitude,longitude,description,photo,status) VALUES (" + obj.id + ",'" + obj.name + "','" + obj.address + "','" + obj.address2 + "','" + obj.latitude + "','" + obj.longitude + "','" + obj.description + "','" + obj.picture + "'," + obj.status + ")", [], function (t, data) {
                        hasUpdated = true;
                    },
                    function(t, e) {
                        alert('2 error table insert settings. ' + e.message);
                    });
                }
            },
            function(t, e) {
                alert('error sql. ' + e.message);
            });

    })

   }, function(){} /*this is the error callback*/
   , function(){
         alert("done");
     } /*this is the success callback*/
);

注意：我将警报放在交易成功回调中。

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