在JS中的函数内设置变量

Question

   var last = 0;

   function grabProducts(searchstring) {
       var last = 0;
       $.post('ajax/products', {
           method: 'search',
           string: searchstring,
           category: $('#search_category').val(),
           sort: $('.sort').val()
       }, function (data) {
           data = $.parseJSON(data);
           $.each(data, function (index, b) {
               last = "dada";
           });
       });
   }
   alert(last);

Gives me alert with "0" . How can i make it set the variable to "dada" ?

Answer 1

You can't make a setup like that work because $.post() is asynchronous . You'll have to put the "alert" in the callback function you pass to $.post() .

var last=0;
function grabProducts(searchstring) {
        var last=0;
        $.post('ajax/products', { method: 'search', string: searchstring, category: $('#search_category').val(), sort: $('.sort').val() }, function(data) {
            data = $.parseJSON(data);
            $.each(data, function(index, b) {
                last = "dada";

            });
            alert(last);
        });
      }

The whole point of the callback, in fact, is to provide you with a way to have code run when the HTTP request is complete.

Answer 2

When you POST something, It needs time for server to respond. Do this:

var last=0;
function grabProducts(searchstring) {
            var last=0;
            $.post('ajax/products', { method: 'search', string: searchstring, category: $('#search_category').val(), sort: $('.sort').val() }, function(data) {
                data = $.parseJSON(data);
                $.each(data, function(index, b) {
                    last = "dada";
                });
                    alert(last);
            });
          }