从 iOS cordova UIwebview 迁移到 wkwebview 禁用异步 ZDE9B9ED78D7E2E1DCEEFFEE780E2F91 执行以支持现有应用程序

Question

In one of our older 'Save Data' examples, we had previously used the following and it was working fine without any issues in cordova UIWebview.

  var filenameID;
  function getFilenameID() {
  $.ajax('/jquery/getdata',   // request url
  {
    success: function (data, status, xhr) {// success callback function
        kp_requestKioskId_callback(data);
   }});
  }
 function kp_requestKioskId_callback(kioskId) {
    filenameID = kioskId.split(" ").join("");
 }
function saveData(fileName, data) {
   getFilenameID();
   kp_FileAPI_writeToFile(filenameID + ".xls", data, "writeFile_callback");
 }

After migrating from UIWebview to WKWebview, In WKWebView since JavaScript code is executed asynchronously, the 'getFilenameID' call is not completed before the 'kp_FileAPI_writeToFile' call is executed, resulting in an undefined filename.

Copying the kp_FileAPI_writeToFile function inside kp_requestKioskId_callback will solve the issue.

But we have many similar kind of functions in our application.

Is there a way to solve or disable the asynchronous javascript execution to avoid major changes on the application

Answer 1

Is there a way to solve or disable the asynchronous javascript execution to avoid major changes on the application

No, in modern browsers/webviews XmlHttpRequest (which is what $.ajax uses behind the scenes) disallows synchronous requests from the main thread. The flag to disable asynchronous behaviour still exists but most browsers will throw an exception if you use it inside the main thread.

You can use synchronous XmlHttpRequest inside web workers, but that isn't making your application synchronous, and you can't use Cordova plugin APIs from web workers either, so you'll find this quite limiting.

The code sample shown you aren't even using the async option, and by default the option is set to true , which means your network request running on UIWebView was also running asynchronously, thus you have is an nondeterministic race condition.

Answer 2

I have never encountered this issue on the UIWebview, after migrating to WKWebview javascript code behaves asynchrously.

For eg: We have 3 API calls which are dependent on one after the other for a single product

Consider if we have 2 products, we are iterating the products in a loop and triggering 3 API for each product.

In WKWebview, it finishes the first thread and at last 2nd flow