book_append_sheet rolling names

.eslintrc

@@ -13,6 +13,7 @@
 		"no-bitwise": 0,
 		"no-console": 0,
 		"no-control-regex": 0,
+		"no-unused-vars": 1,
 		"no-empty": 0,
 		"no-trailing-spaces": 2,
 		"no-use-before-define": [ 1, {

README.md

@@ -1388,7 +1388,25 @@ XLSX.utils.book_append_sheet(workbook, worksheet, sheet_name);
 
 The `book_append_sheet` utility function appends a worksheet to the workbook.
 The third argument specifies the desired worksheet name. Multiple worksheets can
-be added to a workbook by calling the function multiple times.
+be added to a workbook by calling the function multiple times.  If the worksheet
+name is already used in the workbook, it will throw an error.
+
+_Append a Worksheet to a Workbook and find a unique name_
+
+```js
+var new_name = XLSX.utils.book_append_sheet(workbook, worksheet, name, true);
+```
+
+If the fourth argument is `true`, the function will start with the specified
+worksheet name.  If the sheet name exists in the workbook, a new worksheet name
+will be chosen by finding the name stem and incrementing the counter:
+
+```js
+XLSX.utils.book_append_sheet(workbook, sheetA, "Sheet2", true); // Sheet2
+XLSX.utils.book_append_sheet(workbook, sheetB, "Sheet2", true); // Sheet3
+XLSX.utils.book_append_sheet(workbook, sheetC, "Sheet2", true); // Sheet4
+XLSX.utils.book_append_sheet(workbook, sheetD, "Sheet2", true); // Sheet5
+```
 
 _List the Worksheet names in tab order_
 

bits/31_rels.js

@@ -76,7 +76,6 @@ function write_rels(rels)/*:string*/ {
 	return o.join("");
 }
 
-var RELS_EXTERN = [RELS.HLINK, RELS.XPATH, RELS.XMISS];
 function add_rels(rels, rId/*:number*/, f, type, relobj, targetmode/*:?string*/)/*:number*/ {
 	if(!relobj) relobj = {};
 	if(!rels['!id']) rels['!id'] = {};
@@ -87,7 +86,7 @@ function add_rels(rels, rId/*:number*/, f, type, relobj, targetmode/*:?string*/)
 	relobj.Type = type;
 	relobj.Target = f;
 	if(targetmode) relobj.TargetMode = targetmode;
-	else if(RELS_EXTERN.indexOf(relobj.Type) > -1) relobj.TargetMode = "External";
+	else if([RELS.HLINK, RELS.XPATH, RELS.XMISS].indexOf(relobj.Type) > -1) relobj.TargetMode = "External";
 	if(rels['!id'][relobj.Id]) throw new Error("Cannot rewrite rId " + rId);
 	rels['!id'][relobj.Id] = relobj;
 	rels[('/' + relobj.Target).replace("//","/")] = relobj;

bits/51_xlsxmeta.js

@@ -4,6 +4,7 @@ function parse_xlmeta_xml(data, name, opts) {
     return out;
   var pass = false;
   var metatype = 2;
+  var lastmeta;
   data.replace(tagregex, function(x) {
     var y = parsexmltag(x);
     switch (strip_ns(y[0])) {
@@ -21,6 +22,9 @@ function parse_xlmeta_xml(data, name, opts) {
       case "</metadataType>":
         break;
       case "<futureMetadata":
+        for (var j = 0; j < out.Types.length; ++j)
+          if (out.Types[j].name == y.name)
+            lastmeta = out.Types[j];
         break;
       case "</futureMetadata>":
         break;
@@ -59,6 +63,13 @@ function parse_xlmeta_xml(data, name, opts) {
       case "</ext>":
         pass = false;
         break;
+      case "<rvb":
+        if (!lastmeta)
+          break;
+        if (!lastmeta.offsets)
+          lastmeta.offsets = [];
+        lastmeta.offsets.push(+y.i);
+        break;
       default:
         if (!pass && opts.WTF)
           throw new Error("unrecognized " + y[0] + " in metadata");