在异步请求期间难以将数据推送到数组

Question

在下面的代码中，我想知道为什么我的console.log（dataArray）显示一个空数组。我认为可以在ajax请求完成提取数据之前调用console.log。如果是这种情况，有没有办法在调用console.log之前等待ajax请求完成？

var dataArray = [];

var gdpAPI = "https://raw.githubusercontent.com/FreeCodeCamp/ProjectReferenceData/master/GDP-data.json";
  $.getJSON( gdpAPI, {
    format: "json",
    async: false

  })
    .done(function( data ) {


    yearsData = data['data']


    $.each(yearsData, function(i){
       dataArray.push(yearsData[i]);


    })


 });

 console.log(dataArray);

提前谢谢你。 悦

Answer 1

异步代码

您在请求完成之前调用RelativeLayout.LayoutParams relParams = new RelativeLayout.LayoutParams( width, ViewGroup.LayoutParams.WRAP_CONTENT); yourRelativeLayout.setLayoutParams(relParams); 是正确的。只需将您的日志语句放在console.log部分内即可。

Working Fiddle

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.done

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var dataArray = [];

var gdpAPI = "https://raw.githubusercontent.com/FreeCodeCamp/ProjectReferenceData/master/GDP-data.json";
$.getJSON(gdpAPI, {
    format: "json",
    async: false

  })
  .done(function(data) {


    yearsData = data['data']

    $.each(yearsData, function(i) {
      dataArray.push(yearsData[i]);


    })
		console.log('length: ' + dataArray.length,dataArray);

  });

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Answer 2

你必须使用回调函数从函数中获取数据并操纵sendMethedata是你的回调函数的数据

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var dataArray = [];

var gdpAPI = "https://raw.githubusercontent.com/FreeCodeCamp/ProjectReferenceData/master/GDP-data.json";
  $.getJSON( gdpAPI, {
    format: "json",
    async: true

  })
    .done(function( data ) {


   var yearsData = data['data']


    $.each(yearsData, function(i){
       dataArray.push(yearsData[i]);


    });
    sendMethedata(dataArray);

 });

function sendMethedata(data){
console.log(data)
}

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<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>

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