javascript - Leaflet Search for GeoJSON creating duplicate, non-functional buttons

I added a plugin for searching a GeoJSON file in leaflet, but now there are multiple search buttons and they do not recognize any input. I suspect that it is initializing for every single instance of a feature within the GeoJSON file. How do I change my script to only initialize once? (continued from this question: Activating Search Plugin with JS Leaflet

  // load GeoJSON from an external file
$.getJSON("Syriashape.json", function (data) {
// add GeoJSON layer and popups to the map once the file is loaded
var syriaLayer = L.geoJson(data, {
    style: function (feature) {
        return {color: 'red', weight: '1pt'};
    },

    onEachFeature: function (feature, layer) {
        layer.bindPopup(

          "Sheet Number: " + feature.properties.Sheet_Numb + "
" + 

          "Catalog Record: " + "" + feature.properties.LOC_Catalo + "");



    //activate search button

    var searchControl = new L.Control.Search({layer: syriaLayer, propertyName: 'Sheet_Numb', circleLocation:false});

          searchControl.on('search_locationfound', function(e) {

        e.layer.setStyle({});
        if(e.layer._popup)
          e.layer.openPopup();

      }).on('search_collapsed', function(e) {


        featuresLayer.eachLayer(function(layer) { //restore feature color
          featuresLayer.resetStyle(layer);
        }); 
      });

      map.addControl( searchControl );  //inizialize search control


    }


}).addTo(map);
});

Answer

To check if the onEachFeature-function is called more than one time you could use an alert:

...
onEachFeature: function (feature, layer) {

        alert(feature.id);
...

But in general I think there is no need to put the creation of the search control into the onEachFeature-Loop. Just put it at the end of the ajax callback function:

 // load GeoJSON from an external file
  $.getJSON("Syriashape.json", function(data) {
      // add GeoJSON layer and popups to the map once the file is loaded
      var syriaLayer = L.geoJson(data, {
          style: function(feature) {
              return {
                  color: 'red',
                  weight: '1pt'
              };

          },
          onEachFeature: function(feature, layer) {
              layer.bindPopup(

                  "Sheet Number: " + feature.properties.Sheet_Numb + "
" +

                  "Catalog Record: " + "" + feature.properties.LOC_Catalo + "");
          }

      }).addTo(map);


      // When Layer is added...add Search Control ... activate search button
      var searchControl = new L.Control.Search({
          layer: syriaLayer,
          propertyName: 'Sheet_Numb',
          circleLocation: false
      });

      searchControl.on('search_locationfound', function(e) {


          e.layer.setStyle({});
          if (e.layer._popup)
              e.layer.openPopup();

      }).on('search_collapsed', function(e) {

          featuresLayer.eachLayer(function(layer) { //restore feature color
              featuresLayer.resetStyle(layer);
          });
      });


      map.addControl(searchControl); //inizialize search control



  });