How can I make a JavaScript synchronous call to the server?
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How can I get jQuery to perform a synchronous, rather than asynchronous, AJAX request?
我有一个返回初始化数据的方法。它首先检查会话存储。如果在那里找不到数据，它会调用服务器来获取数据。代码如下：
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 | function getInitializationData() { // Check local storage (cache) prior to making a server call. // Assume HTML 5 browser because this is an Intranet application. if (!sessionStorage.getItem("initialData")) { // The browser doesn't have the initialization data, // so the client will call the server to get the data. // Note: the initialization data is complex but // HTML 5 storage only stores strings. Thus, the // code has to convert into a string prior to storage. $.ajax({ url:"../initialization.x", type:"POST", dataType:"json", timeout: 10000, error: handleError, success: function(data) { sessionStorage.setItem("initialData", JSON.stringify(data)); } }); } // convert the string back to a complex object return JSON.parse(sessionStorage.getItem("initialData")); } |
问题是成功函数几乎总是在方法返回后执行。如何使服务器调用同步，以便成功函数必须在getInitializationData方法的返回语句之前执行？
使用
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 | function getInitializationData() { // Check local storage (cache) prior to making a server call. // Assume HTML 5 browser because this is an Intranet application. if (!sessionStorage.getItem("initialData")) { // The browser doesn't have the initialization data, // so the client will call the server to get the data. // Note: the initialization data is complex but // HTML 5 storage only stores strings. Thus, the // code has to convert into a string prior to storage. $.ajax({ url:"../initialization.x", type:"POST", dataType:"json", timeout: 10000, async: false, error: handleError, success: function(data) { sessionStorage.setItem("initialData", JSON.stringify(data)); } }); } // convert the string back to a complex object return JSON.parse(sessionStorage.getItem("initialData")); } |