Replace collections map by native map

Author: furstenheim-geoblink

index.js

@@ -14,7 +14,6 @@
   "author": "Ber-Lin Lai <berlin.lai@gmail.com>",
   "license": "BSD",
   "dependencies": {
-    "collections": "^3.0.0",
     "node-zip": "1.x"
   },
   "devDependencies": {

package.json

@@ -145,10 +145,16 @@ var addStringCell = function(sheet, cellRef, value, styleIndex){
   if (typeof value ==='string'){
     value = value.replace(/&/g, "&amp;").replace(/'/g, "&apos;").replace(/>/g, "&gt;").replace(/</g, "&lt;");
   }
-  var i = sheet.shareStrings.get(value, -1);
+	// TODO there is no default value in js map
+	var i
+	if (!sheet.shareStrings.has(value)) {
+		i = -1
+	} else {
+		i = sheet.shareStrings.get(value)
+	}
 	if ( i< 0){
-    i = sheet.shareStrings.length;
-  	sheet.shareStrings.add(value, i);
+    i = sheet.shareStrings.size;
+  	sheet.shareStrings.set(value, i);
     sheet.convertedShareStrings += "<x:si><x:t>"+value+"</x:t></x:si>";
 	}
 	return '<x:c r="'+cellRef+'" s="'+ styleIndex + '" t="s"><x:v>'+i+'</x:v></x:c>';