How to write async code in my project

Question

Could you please provide an example which makes this code asynchronous 1)i have to read file by $http.get function from the server 2) read the file to an array 3)process it (reBuild it) 4) and show progress bar on every action

so the code is :

$http.get(filename).success(function (data) {
     words = data.split(/\n| /);
     reBuild(words) //this action takes at least 5 seconds
     Process(words) // this action takes at least 4 seconds
})

and i want to make it asynchronous, i dont want to freeze my thread when reBuild and Process have been excuted Any idea how to do this?

Answer 1

您可以处理事件，但是最简单的方法是使用setTimeout并分批处理长循环。

Answer 2

Assuming that 'reBuild' has to finish before 'Process' can run, the best way to approach it IMO is to make reBuild and Process functions return promises instead. Promises are a javascript way of dealing with async events - http://docs.angularjs.org/api/ng .$q .

For example, for your reBuild method instead of having something like this:

var reBuild = function(words) {
  // 5 second operation here
  return words;
}

Do it like this: (You'll need to inject the $q and $timeout services into your controller to make it work)

var reBuild = function(words) {
   var deferred = $q.defer();

   $timeout(function() {
       // do 5 second operation
       deferred.resolve(words);
   });

   return deferred.promise;
}

And then in your controller you can do:

$http.get(filename).success(function (data) {
     words = data.split(/\n| /);
     reBuild(words).then(function(reBuiltWords) {
         Process(reBuiltWords);
     }); 
})