javascript中的范围变量,jquery

Question

我试图在我的ajax响应中访问变量'dimensions'但是无法获得它.我不想让这个变量全局化.以下是我的代码

  $(document).ready(function(){
  $('#submittext').click(function(){
   var dimensions;
   $.ajax({
     type: "GET",
     url: "bin/getcontentsize.php",
     data: findContentsize,
     success: function(response){
       //want to access dimensions here to assign response and some calculation(but not able to access it)
     }
     });
   //so i can use here
  });
  });

Answer 1

在这种情况下,您可以dimensions在启动ajax请求后立即从ajax回调和代码中访问变量.可以在这两种上下文中访问该变量.

最有可能导致问题的是时机.success在ajax请求完成后,该方法将异步运行.最好将此视为稍后执行.但是,紧接着$.ajax调用后的代码将立即执行.因此success,当dimensions变量运行时,您将看不到处理程序对变量的任何影响.

如果您希望使用方法dimensions计算的值运行success代码,则需要从success回调中调用该代码.例如

$('#submittext').click(function(){

   var handleNewDimensions = function (dimensions) {
     // Code that used to be after the $.ajax line
   }

   $.ajax({
     type: "GET",
     url: "bin/getcontentsize.php",
     data: findContentsize,
     success: function(response){
       var dimensions = doTheCalculation(...);

       // Call the code which needs to deal with the new dimensions
       handleNewDimensions(dimensions);
     }
   });