Question

我对AJAX调用还不太熟悉，无法知道它是如何工作的。如果我有一个数组A并且在上面使用A.filter()，那么过滤器中的AJAX调用将如何工作？我相信，该数组用于同步填充模板。

// Event calls function to filter list on page.
// Function calls filterArray(arrayList, objFilters)

async_fetch: function(string)
{
  // Utilizes $.ajax() to retrieve a JSON array
  var deferred = $.Deferred();

  $.ajax({
    url: ...,
    dataType: "json",
    success: function(data) {
      var response = data;
      deferred.resolve(data);
    },
    error: function(data)
    {
      //...
      deferred.reject(msg);
    }
  });
  return deferred;
};

filterArray: function(list, filters)
{
  var filteredList = list.filter(function(item) {
    for(var key in filters) {
      // Actions for each of multiple filters to compare against...
      else if(key == 'FILTER_X') {
        var data = async_fetch(item.name);
        // Use data to arrive at a determination, where true means I don't want to include this item in the filtered list
        if(determination)
          return false;
      }
    }
  };
  return filteredList;
};

// Results of filterArray() are passed along to a template within Backbone 
//   to redraw a segment of HTML on the page.

过滤器调用将仅同步等待AJAX调用完成吗？列表是否会被过滤掉并返回，并且AJAX调用必须挂接到过滤后的列表中，并且稍后实质上完成过滤？我应该只构建一个不是异步的async_fetch()版本吗？

Answer 1

您将需要.then()或.done()通话，例如 ....

 async_fetch(item.name).then(function(data){
        if (data.determination)
          // do something
    })

....

Answer 2

您好，您可以在过滤数据后解决承诺。像这样的例子希望对您有帮助。

$(document).ready(function(){
  function async_fetch(string)
{
  // Utilizes $.ajax() to retrieve a JSON array
  var deferred = $.Deferred();

  $.ajax({
    url: string,//your URL
    dataType: "json",
    success: function(data) {
      var filterdData= filterArray(data);
      deferred.resolve(filterdData);
    },
    error: function(data)
    {
      //...
      deferred.reject(msg);
    }
  });
  return deferred;
};

 function filterArray(data)
{
  var filteredList = data.filter(function(item) {
   //filter whatever you want
    })
  return filteredList;
}

async_fetch(url).then(function(response){
  //now you will get the filterd data
  console.log(response);
}) 
});

Answer 3

您可以在async/await的帮助下进行以下操作：-

const filterArray = async function (list, filters) {
    var filteredListPromise = list.filter(async function (item) {
        for (var key in filters) {
            // Actions for each of multiple filters to compare against...
            if (key == 'FILTER_X') {
                return arriveAtDetermination(item.name);
            }
            else {
                //other filters
            }
        }
    });
    return Promise.all(filteredListPromise);
};

async function arriveAtDetermination(name) {
    let data = await async_fetch(name);
    return determination ? true : false;//your logic
}

//Now you can filter like

filterArray(list, filters).then(result => {
    console.log(result);
}).catch(err => {
    console.log(err);
})

Javascript：如何处理数组过滤器操作中的jQuery.ajax函数调用？

3 个答案: