如何解决websql中的异步问题
1.首先websql openDatabase（）方法打开数据库的其结果必然以异步方式返回结果，openDatabaseSync()方法可以同步方式打开数据库，但是貌似safari游览器中找不到这样的一个方法。
To get an object implementing DatabaseSync you have to call openDatabaseSync(...) instead ofopenDatabase(...). I don't know about the iPhone, or what the oDB object you have is, but according to spec you only get the openDatabaseSync method in a WebWorker and not in the normal web browser window. Certainly XMLHttpRequest has demonstrated that potentially-length synchronous operations in the UI thread are not a good idea.
2.看了老外的另外一个方案：http://stackoverflow.com/questions/3903155/synchronous-query-to-web-sql-database
发现其实可以直接写在回调函数中不必拆分成多个函数，这样就可以解决异步的问题了，如下（所有代码逻辑都在回调函数中完成）：
function
getFolder(id, callback) {
var
data = [];
ldb.transaction(function
(tx) {
tx.executeSql('SELECT
* FROM folders where id=?',
[id],
function
(tx, results) {
if
(results.rows && results.rows.length) {
for
(i = 0; i < results.rows.length; i++) {
data.push(results.rows.item(i));
}
}
if
( typeof(callback)
== 'function'
) callback(data);
},
function
(tx, error) {
console.log(error);
});
});
摘自 CF西西的专栏
补充：Web开发 , 其他 ,
