Update columnsearch

Added option for specifying which columns to display the search input or select
Added additional examples

features/columnsearch

@@ -10,14 +10,44 @@
  */
 
 /**
- * Example usage
+ * Example usage 1
  * @example
+ * zero configuration - displays a select in the footer of each column
  * var table = $('#table_id').DataTable();
- * columnSearch =
- *     new $.fn.dataTable.ColumnSearch(table, {
- *         searchElementType: 'select',
- *         rowId: 'rowSearch'
- *     });
+ * $.fn.dataTable.ColumnSearch(table);
+ */
+/**
+ * Example usage 2
+ * @example
+ * select search targetting specific columns
+ * var table = $('#table_id').DataTable();
+ * $.fn.dataTable.ColumnSearch(table, {
+ *      selectAllText: 'Any',
+ *      cols: [0,3,5]
+ * }); 
+ */
+/**
+ * Example usage 3
+ * @example
+ * text search with headings as placeholder
+ * var table = $('#table_id').DataTable();
+ * $.fn.dataTable.ColumnSearch(table, {
+ *      searchElementType: 'text',
+ *      displayHeadingAsPlaceholder: true
+ * }); 
+ */
+/**
+ * Example usage 4
+ * @example
+ * text search targetting the header or 
+ * footer row specified by rowId, and
+ * targetting specific columns
+ * var table = $('#table_id').DataTable();
+ * $.fn.dataTable.ColumnSearch(table, {
+ *      searchElementType: 'Any',
+ *      rowId: 'rowSearch',
+ *      cols: [0,3,5]
+ * }); 
  */
 (function ($) {
     var ColumnSearch = function (dt, options) {
@@ -27,16 +57,20 @@
         else initTextSearch();
 
         function initSelectSearch() {
-            if (opts.rowId != null) {
+            if (opts.rowId !== null) {
                 $('tr#' + opts.rowId + ' th', dt.table().node()).each(function(i) {
-                    var column = dt.column(i);
-                    appendSelectTo($(this), column);
+                    if (opts.cols.indexOf(i) !== -1) {
+                        var column = dt.column(i);
+                        appendSelectTo($(this), column);
+                    }
                 });
             }
             else {
-                dt.columns().every( function () {
-                    var column = this;
-                    appendSelectTo($(column.footer()).empty(), column);
+                dt.columns().every( function (i) {
+                    if (opts.cols.indexOf(i) !== -1) {
+                        var column = this;
+                        appendSelectTo($(column.footer()).empty(), column);
+                    }
                 } );
             }            
         }
@@ -60,20 +94,24 @@
         }
 
         function initTextSearch() {
-             if (opts.rowId != null) {
+             if (opts.rowId !== null) {
                 $('tr#' + opts.rowId + ' th', dt.table().node()).each(function(i) {
-                    var column = dt.column(i);
-                    var header = $(column.header());
-                    var headerText = header.text();
-                    appendTextInputTo($(this), column, opts.displayHeadingAsPlaceholder ? headerText : '');
+                    if (opts.cols.indexOf(i) !== -1) {
+                        var column = dt.column(i);                    
+                        var header = $(column.header());
+                        var headerText = header.text();
+                        appendTextInputTo($(this), column, opts.displayHeadingAsPlaceholder ? headerText : '');
+                    }
                 });
             }
             else {
-                dt.columns().every( function () {
-                    var column = this;
-                    var footer = $(column.footer());
-                    var footerText = footer.text();
-                    appendTextInputTo(footer.empty(), column, opts.displayHeadingAsPlaceholder ? footerText : '');
+                dt.columns().every( function (i) {
+                    if (opts.cols.indexOf(i) !== -1) {
+                        var column = this;
+                        var footer = $(column.footer());
+                        var footerText = footer.text();
+                        appendTextInputTo(footer.empty(), column, opts.displayHeadingAsPlaceholder ? footerText : '');
+                    }
                 } );
             }            
         }
@@ -94,7 +132,9 @@
     ColumnSearch.defaults = {
         searchElementType: 'select',
         selectAllText: 'All',
-        displayHeadingAsPlaceholder: false
+        displayHeadingAsPlaceholder: false,
+        rowId: null,
+        cols: []
     };
 
     $.fn.dataTable.ColumnSearch = ColumnSearch;