在变量中输入ajax结果的函数

I have a problem with this code. This happens: just launch the code from console.log I get null, if I press the update button function works.

我有这个代码的问题。发生这种情况:只是从console.log启动代码我得到null,如果我按下更新按钮功能工作。

why is this happening? how do I fix?

为什么会这样?我该如何解决?

var urljson = "data_json.php";
var data = null;
var jqXHR = $.ajax
({
  type: "GET",
  url: urljson,
  dataType: 'json',
  success: successHandler

});
function successHandler(result) {
     data = result; 
 }

function update(){
var jqXHR = $.ajax
({
  type: "GET",
  url: urljson,
  dataType: 'json',
  success: successHandler

});
function successHandler(result) {
     data = result; 
 }
}

$(document).ready(function(){   

 console.log(data) //// null

});


document.getElementById('update').addEventListener('click', function() {

update();

console.log(data) //// Array [ Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, other 3213… ]

});

2 个解决方案

#1

$.ajax() returns results asynchronously. Use success handler or .then() chained to $.ajax() to process response returned from request.

$ .ajax()以异步方式返回结果。使用成功处理程序或.then()链接到$ .ajax()来处理从请求返回的响应。

function update() {
  var jqXHR = $.ajax({
    type: "GET",
    url: urljson,
    dataType: "json",
    success: successHandler    
  });

  function successHandler(result) {
    data = result;
    // do stuff with `data` here
    console.log(data);
  }
}

$(document).ready(update);

jsfiddle https://jsfiddle.net/89jkzzyk/

#2

When the page loads, update() is not getting called, thus data is null. Add your function call to $(document).ready() and it should work.

页面加载时,不会调用update(),因此数据为空。将函数调用添加到$(document).ready(),它应该可以工作。

#1