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分享一篇改写成传统的回调函数实例教程

程序员文章站 2022-05-01 12:53:40
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改写前:

百度地图中坐标转换的JavaScript API示例官方示例如下:

var points = [new BMap.Point(116.3786889372559,39.90762965106183),              new BMap.Point(116.38632786853032,39.90795884517671),              new BMap.Point(116.39534009082035,39.907432133833574),              new BMap.Point(116.40624058825688,39.90789300648029),              new BMap.Point(116.41413701159672,39.90795884517671)
];//地图初始化var bm = new BMap.Map("allmap");
bm.centerAndZoom(new BMap.Point(116.378688937,39.9076296510), 15);//坐标转换完之后的回调函数translateCallback = function (data){  if(data.status === 0) {for (var i = 0; i < data.points.length; i++) {
        bm.addOverlay(new BMap.Marker(data.points[i]));
        bm.setCenter(data.points[i]);
    }
  }
}
setTimeout(function(){var convertor = new BMap.Convertor();
    convertor.translate(points, 1, 5, translateCallback)
}, 1000);

改写后:

将上述代码改写为传统的JavaScript回调函数形式:

function translate(points,callback){  var convertor=new BMap.Convertor();
  convertor.translate(points, 1, 5, callback)
  translateCallback = function (data){if(data.status === 0) {      var res=[]; //res用来存放转换后的points数组  for (var i = 0; i < data.points.length; i++) {
          bm.addOverlay(new BMap.Marker(data.points[i]));
          res.push(data.points[i]);
      }
      callback(res)
    }
  }
}//再调用translate函数,translate(points,function(data){
    console.log(data); //data为转换后的points数组})

改写后translate函数接受两个参数,第一个参数为原始的百度points数组,第二个参数传入一个回调函数。

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