jquery的选择器功能
1 :lt(index) selector
一组元素选择index之前的元素，若index<0 则倒着选过来
http://api.jquery.com/lt-selector/
<!doctype html> <html lang="en"> <head> <meta charset="utf-8"> <title>lt demo</title> <script src="//code.jquery.com/jquery-1.10.2.js"></script> </head> <body> <table border="1"> <tr><td>TD #0</td><td>TD #1</td><td>TD #2</td></tr> <tr><td>TD #3</td><td>TD #4</td><td>TD #5</td></tr> <tr><td>TD #6</td><td>TD #7</td><td>TD #8</td></tr> </table> <script> $( "td:lt(4)" ).css( "backgroundColor", "yellow" ); $( "td:lt(-2)" ).css( "color", "red" ); </script> </body> </html>