Added support for .eq(-N), .first(), and .last(). Fixes #2164 and #4188.

jeresig · jeresig · commit 9de120e6d7cf · 2009-09-09T00:21:21.000Z
diff --git a/src/traversing.js b/src/traversing.js
@@ -78,7 +78,17 @@ jQuery.fn.extend({
 	},
 
 	eq: function( i ) {
-		return this.slice( i, +i + 1 );
+		return i === -1 ?
+			this.slice( i ) :
+			this.slice( i, +i + 1 );
+	},
+
+	first: function() {
+		return this.eq( 0 );
+	},
+
+	last: function() {
+		return this.eq( -1 );
 	},
 
 	slice: function() {
diff --git a/test/unit/traversing.js b/test/unit/traversing.js
@@ -203,7 +203,7 @@ test("prev([String])", function() {
 });
 
 test("slice()", function() {
-	expect(6);
+	expect(7);
 
 	var $links = jQuery("#ap a");
 
@@ -213,8 +213,20 @@ test("slice()", function() {
 	isSet( $links.slice(-1), q("mark"), "slice(-1)" );
 
 	isSet( $links.eq(1), q("groups"), "eq(1)" );
-
 	isSet( $links.eq('2'), q("anchor1"), "eq('2')" );
+	isSet( $links.eq(-1), q("mark"), "eq(-1)" );
+});
+
+test("first()/last()", function() {
+	expect(4);
+
+	var $links = jQuery("#ap a"), $none = jQuery("asdf");
+
+	isSet( $links.first(), q("google"), "first()" );
+	isSet( $links.last(), q("mark"), "last()" );
+
+	isSet( $none.first(), [], "first() none" );
+	isSet( $none.last(), [], "last() none" );
 });
 
 test("map()", function() {
