jQuery getJSON problem

$.getJSON( "http://yoolk.dev:3012/categories?callback=?", function(data) {
    console.log(data)
 }
);

I have the code above in order 开发者_开发问答to get json data, but callback function seems not be working. Anyone can help? Thanks

---

if the request fails, your callback wont be called. you can use something like the example below to detect the failure. jquery will not call any error handlers in case of a jsonp failure... so, one can implement a timer that checks the result...

here, task.run does the ajax request, and the checkStatus function checks the result.

var task = {
  complete: 0,
  timeout: 5000,

  run: function() {
    $.ajax({
      type: 'get',
      url: 'http://www.yahoo.com',
      dataType: 'jsonp',
      timeout: this.timeout,
      complete: function(req, status) {
        this.complete = 1
        if (status == "success") {
          alert('Success');
        } else {
          alert('Error: ' + status)
        }
      }
    })

    var o = this
    setTimeout(function() {o.checkStatus()}, this.timeout + 1000)
  },

  checkStatus: function() {
    if (!this.complete) {
      alert('Error: Request did not complete')
    }
  }
}

task.run()