javascript - 编译 CoffeeScript 时添加不需要的 js 代码

Question

我是 CoffeeScript 的新手，我有一个 CoffeeScript 代码

getProviderListDisplayValues:(domainId) ->      
    displayValues = []
    $.ajax 
        contentType: 'application/json',
        url: "/Services/ListProviders?domainid=#{domainId}",
        success: (data) ->          
            for oneResponse in data
                displayValues.push oneResponse.name     
    displayValues

编译为

CounselorHome.prototype.getProviderListValues = function(domainId) {
   var values;
   values = [];
   $.ajax({
     contentType: 'application/json',
     url: "/Services/ListProviders?domainid=" + domainId,
     success: function(data) {
       var oneResponse, _i, _len, _results;
       _results = [];
       for (_i = 0, _len = data.length; _i < _len; _i++) {
         oneResponse = data[_i];
         _results.push(values.push(oneResponse.id));
       }
       return _results;
     }
   });
   return values;
};

我只想将值推送到 values[] 和 displayValues[] 但为什么要创建 _results[] 数组？它会影响浏览器的效率吗？有没有什么方法可以去掉这些不必要的代码呢？也许可以，通过编辑我的 CoffeeScript 。

编辑:工作条件

但是当我将警报代码设置为

 $.ajax 
        contentType: 'application/json',
        url: "/Services/ListProviders?domainid=#{domainId}",
        success: (data) ->          
            for oneResponse in data
                displayValues.push oneResponse.name     
 alert displayValues
 displayValues

此代码有效，我可以检索所需的数据。

Answer 1

除此之外your code wouldn't work anyway ，_results是由于coffescripts隐式函数返回值而生成的 - 和 loops are only expressions以及生成数组。文档指出:

Sometimes functions end with loops that are intended to run only for their side-effects. Be careful that you're not accidentally returning the results of the comprehension in these cases, by adding a meaningful return value — like true — or null, to the bottom of your function.

因此可以通过编写来创建您期望的 javascript

…
    success: (data) ->
        for oneResponse in data
            displayValues.push oneResponse.name
        return
…

(“尾随 return 和 return undefined 现已优化。” - 自版本 1.0.1 起)；
另请参阅Is there any way to not return something using CoffeeScript?

但是，您真正想要的是:

getProviderListDisplayValues:(domainId) ->
    $.ajax
        contentType: 'application/json',
        url: "/Services/ListProviders?domainid=#{domainId}"
    .then (data) ->          
        for oneResponse in data
            oneResponse.name

…

getProviderListDisplayValues(…).then (displayValues) ->
    …