Allow optional row conversion function to d3_dsv.

d3.js

@@ -5234,14 +5234,15 @@ d3 = function() {
   }
   function d3_dsv(delimiter, mimeType) {
     var reFormat = new RegExp('["' + delimiter + "\n]"), delimiterCode = delimiter.charCodeAt(0);
-    function dsv(url, callback) {
-      var xhr = d3.xhr(url, mimeType, callback), row;
+    function dsv(url, row, callback) {
+      if (arguments.length < 3) callback = row, row = null;
+      var xhr = d3.xhr(url, mimeType, callback);
       xhr.row = function(_) {
         if (!arguments.length) return row;
         xhr.response((row = _) == null ? response : typedResponse(_));
         return xhr;
       };
-      return xhr.row(null);
+      return xhr.row(row);
     }
     function response(request) {
       return dsv.parse(request.responseText);

src/dsv/dsv.js

@@ -2,9 +2,9 @@ function d3_dsv(delimiter, mimeType) {
   var reFormat = new RegExp("[\"" + delimiter + "\n]"),
       delimiterCode = delimiter.charCodeAt(0);
 
-  function dsv(url, callback) {
-    var xhr = d3.xhr(url, mimeType, callback),
-        row;
+  function dsv(url, row, callback) {
+    if (arguments.length < 3) callback = row, row = null;
+    var xhr = d3.xhr(url, mimeType, callback);
 
     xhr.row = function(_) {
       if (!arguments.length) return row;
@@ -12,7 +12,7 @@ function d3_dsv(delimiter, mimeType) {
       return xhr;
     };
 
-    return xhr.row(null);
+    return xhr.row(row);
   }
 
   function response(request) {

test/dsv/csv-test.js

@@ -14,19 +14,33 @@ suite.addBatch({
       });
     },
     "invokes the callback with the parsed CSV": function(csv) {
-      assert.deepEqual(csv, [{"Hello":42,"World":"\"fish\""}]);
+      assert.deepEqual(csv, [{"Hello":"42","World":"\"fish\""}]);
     },
     "overrides the mime type to text/csv": function(csv) {
       assert.equal(XMLHttpRequest._last._info.mimeType, "text/csv");
     },
-    "": {
+    "specifying a row conversion function": {
+      topic: function() {
+        var cb = this.callback;
+        d3.csv("test/data/sample.csv", function(row) {
+          row.Hello = -row.Hello;
+          return row;
+        }, function(error, csv) {
+          cb(null, csv);
+        });
+      },
+      "invokes the callback with the parsed CSV": function(csv) {
+        assert.strictEqual(csv[0].Hello, -42);
+      }
+    },
+    "attempting to load a file that does not exist": {
       topic: function() {
         var cb = this.callback;
         d3.csv("//does/not/exist.csv", function(error, csv) {
           cb(null, csv);
         });
       },
-      "invokes the callback with undefined when an error occurs": function(csv) {
+      "invokes the callback with undefined": function(csv) {
         assert.isUndefined(csv);
       }
     }