如何将json文件实现为javascript

我正在尝试将一个本地海量数据json文件实现到我的javascript文件中。我尝试了这个，但没有成功。返回0

这个函数的概念是当我输入lat和long时，它应该返回与它们相关的网格代码

    function lookupGridcodeByLatAndLong(lat, long)
{
  let gridcode = 0;
$.getJSON('example.json',function( data ) {

  var result = data.find(x => x.lat == lat && x.long == long)
  if (result) { gridcode = result.GRIDCODE;}
});
return gridcode;
};

这就是我的数据的样子

 [{"GRIDCODE":1765,"lat":35.916,"long":-5.401},{"GRIDCODE":1807,"lat":35.907,"long":-5.467},{"GRIDCODE":1798,"lat":35.907,"long":-5.459},{"GRIDCODE":1546,"lat":35.907,"long":-5.409},{"GRIDCODE":1667,"lat":35.907,"long":-5.401},{"GRIDCODE":1729,"lat":35.907,"long":-5.384},{"GRIDCODE":1756,"lat":35.899,"long":-5.484},{"GRIDCODE":1773,"lat":35.899,"long":-5.476},{"GRIDCODE":1828,"lat":35.899,"long":-5.467},{"GRIDCODE":1842,"lat":35.899,"long":-5.459},{"GRIDCODE":1779,"lat":35.899,"long":-5.451},{"GRIDCODE":1728,"lat":35.899,"long":-5.442},{"GRIDCODE":1773,"lat":35.899,"long":-5.434},{"GRIDCODE":1609,"lat":35.899,"long":-5.426}]

---

这是因为

$.getJSON

正在异步运行

您需要使用回调或

使用承诺（首选方式）

---

这是因为getJSON调用是异步的。您应该执行基于承诺的实现

@MukeshKeshu Great！：）<代码>函数LookupGridCodeByLandLong（lat，long）{返回新承诺（（resolve，reject）=>{$.getJSON（'example.json'，函数（data）{var result=data.find（x=>x.lat==lat&&x.long==long）if（result）{resolve（result.GRIDCODE）}else{reject（）}}}；$（“#Btn”）。单击（函数（）{var lat=document.getElementById（“lat”）.value，long=document.getElementById（“long”）.value；var result=lookupGridCodeByLandLong（lat，long）；$（“#result”）.html（result）；}）否。您不能只将返回值赋给

#result

您需要使用

。然后在那里执行
#result
的赋值。@MukeshKeshu有什么想法吗请$（“#Btn”）。单击（function（）{var lat document=document.getElementById（“lat”）.value；long=document.getElementById（“long”）.value；lookupGridCodeByAndLong（lat，long）.then（result=>{$（“#result”）.html（result）}）；
function lookupGridcodeByLatAndLong(lat, long, done) {
  $.getJSON('example.json', function(data) {
    var result = data.find(x => x.lat == lat && x.long == long)

    done(result ? result.GRIDCODE : 0)
  })
}

lookupGridcodeByLatAndLong(lat, long, function(gridcode) {
  // do something with gridcode
})    

function lookupGridcodeByLatAndLong(lat, long) {
  return new Promise((resolve, reject) => {
    $.getJSON('example.json', function(data) {
      var result = data.find(x => x.lat == lat && x.long == long)

      if (result) {
        resolve(result.GRIDCODE)
      } else {
        reject()
      }
  })
}

lookupGridcodeByLatAndLong(lat, long)
.then(gridcode => {
  // do something with gridcode
})