javascript - 求解，google map 错误etMap: not an instance of Map

Question

function search_map(){
  var keyword=$("#keyword").val();
    $.ajax({
      url: "app_maps.php",
      dataType:"json",
      type:"POST",
      data:{
            "keyword":keyword,
            "type":"search"
           }
     }).done(function(msg){
      if(msg){
        var name=msg.Name;
        var address=msg.address;
        var j=1;
        //下面这一段是copy来的
        var beaches = [
          ['Bondi Beach', 24.1424631, 120.6468703, 4],
          ['Coogee Beach',24.168649, 120.6490875, 5],
          ['Cronulla Beach', 24.1501231, 120.6490875, 3],
          ['Manly Beach', 24.1501231, 120.6391684, 2],
          ['Maroubra Beach', 24.1501231,120.6391684, 1]
        ];
        for (var i = 0; i < beaches.length; i++) {
          var beach = beaches[i];
          var marker = new google.maps.Marker({
            position: {lat: beach[1], lng: beach[2]},
            map: map,
        
            title: beach[0],
            zIndex: beach[3]
          });
         }
        }
     });
}

我写了一个function 重点是把捞数据库里的东西。这一段一直标示不起来，后来我copy了一段程序 这段程序放在function 外是可以正常运作的，但放在function内，却是无法运作会显示：InvalidValueError: setMap: not an instance of Map; and not an instance of StreetViewPanorama

当然也爬了文 把map 换成 setMap ，这时没有错误讯息了，但还是没有标示。整段的程序是：

$(document).ready(function(){
    var taipei = new google.maps.LatLng(25.08, 121.45);
    var latlng=new google.maps.LatLng(24.1644833, 120.6575312);
    var mapOptions = {   
         zoom: 17,   
         mapTypeId: google.maps.MapTypeId.ROADMAP,   
    };   
    var map = new google.maps.Map(document.getElementById('mymap'),   
  mapOptions); 
    var marker = new google.maps.Marker({
                title: "现在位置", //显示文字
                icon:'images/big.png',
                 map: map //指定要放置的地图对象
                });
    if(window.navigator.geolocation){   
        var geolocation=window.navigator.geolocation;   
        geolocation.getCurrentPosition(getPositionSuccess);   
    }else{   
        alert("你的浏览器不支持地理定位");   
        map.setCenter(taipei);   
    }   

    function getPositionSuccess(position){   
        initialLocation = new     google.maps.LatLng(position.coords.latitude,position.coords.longitude);   
        //定位到目前位置   
        map.setCenter(initialLocation);
        marker.setPosition(initialLocation);   
    } 

});
function search_map(){
  var keyword=$("#keyword").val();
    $.ajax({
              url: "app_maps.php",
          dataType:"json",
          type:"POST",
          data:{
            "keyword":keyword,
            "type":"search"
               }
    }).done(function(msg){
  if(msg){
        var name=msg.Name;
        var address=msg.address;
        var j=1;
       var beaches = [
          ['Bondi Beach', 24.1424631, 120.6468703, 4],
          ['Coogee Beach',24.168649, 120.6490875, 5],
          ['Cronulla Beach', 24.1501231, 120.6490875, 3],
          ['Manly Beach', 24.1501231, 120.6391684, 2],
          ['Maroubra Beach', 24.1501231,120.6391684, 1]
        ];
        for (var i = 0; i < beaches.length; i++) {
          var beach = beaches[i];
          var marker = new google.maps.Marker({
            position: {lat: beach[1], lng: beach[2]},
            map: map,
        
            title: beach[0],
            zIndex: beach[3]
          });

        }

  }

  

                   
    });
}