Fix for #883

src/jquery/coreTest.js

@@ -102,7 +102,7 @@ test("attr(Hash)", function() {
 });
 
 test("attr(String, Object)", function() {
-	expect(6);
+	expect(7);
 	var div = $("div");
 	div.attr("foo", "bar");
 	var pass = true;
@@ -110,6 +110,8 @@ test("attr(String, Object)", function() {
 	  if ( div.get(i).getAttribute('foo') != "bar" ) pass = false;
 	}
 	ok( pass, "Set Attribute" );
+
+	ok( $("#foo").attr({"width": null}), "Try to set an attribute to nothing" );	
 	
 	$("#name").attr('name', 'something');
 	ok( $("#name").attr('name') == 'something', 'Set name attribute' );

src/jquery/jquery.js

@@ -1281,7 +1281,7 @@ jQuery.extend({
 			var exclude = /z-?index|font-?weight|opacity|zoom|line-?height/i;
 
 			// Handle passing in a number to a CSS property
-			if ( value.constructor == Number && type == "curCSS" && !exclude.test(prop) )
+			if ( value && value.constructor == Number && type == "curCSS" && !exclude.test(prop) )
 				return value + "px";
 
 			return value;