Landing pull request 509. Add a comment explaining the use of document.getElementsByT...

More Details:
 - https://github.com/jquery/jquery/pull/509

diff --git a/src/support.js b/src/support.js
index 284465974aa0580eeb221c94738f32061b0f01b4..6a77e449cbfb5fad2aad221e5040a49dc61018ee 100644 (file)
--- a/src/support.js
+++ b/src/support.js
@@ -122,7 +122,7 @@ jQuery.support = (function() {
                div.cloneNode( true ).fireEvent( "onclick" );
        }
 
-       // Check if a radio maintains it's value
+       // Check if a radio maintains its value
        // after being appended to the DOM
        input = document.createElement("input");
        input.value = "t";
@@ -142,7 +142,11 @@ jQuery.support = (function() {
        // Figure out if the W3C box model works as expected
        div.style.width = div.style.paddingLeft = "1px";
 
-       body = document.getElementsByTagName( "body" )[ 0 ];
+       // We don't want to do body-related feature tests on frameset
+       // documents, which lack a body. So we use
+       // document.getElementsByTagName("body")[0], which is undefined in
+       // frameset documents, while document.body isn’t. (7398)
+       body = document.getElementsByTagName("body")[ 0 ];
        // We use our own, invisible, body unless the body is already present
        // in which case we use a div (#9239)
        testElement = document.createElement( body ? "div" : "body" );
@@ -157,8 +161,8 @@ jQuery.support = (function() {
        if ( body ) {
                jQuery.extend( testElementStyle, {
                        position: "absolute",
-                       left: "-1000px",
-                       top: "-1000px"
+                       left: "-999px",
+                       top: "-999px"
                });
        }
        for ( i in testElementStyle ) {