{"rowid": 192, "title": "Cleaner Code with CSS3 Selectors", "contents": "The parts of CSS3 that seem to grab the most column inches on blogs and in articles are the shiny bits. Rounded corners, text shadow and new ways to achieve CSS layouts are all exciting and bring with them all kinds of possibilities for web design. However what really gets me, as a developer, excited is a bit more mundane. \n\nIn this article I\u2019m going to take a look at some of the ways our front and back-end code will be simplified by CSS3, by looking at the ways we achieve certain visual effects now in comparison to how we will achieve them in a glorious, CSS3-supported future. I\u2019m also going to demonstrate how we can use these selectors now with a little help from JavaScript \u2013 which can work out very useful if you find yourself in a situation where you can\u2019t change markup that is being output by some server-side code.\n\nThe wonder of nth-child\n\nSo why does nth-child get me so excited? Here is a really common situation, the designer would like the tables in the application to look like this:\n\n\n\nSetting every other table row to a different colour is a common way to enhance readability of long rows. The tried and tested way to implement this is by adding a class to every other row. If you are writing the markup for your table by hand this is a bit of a nuisance, and if you stick a row in the middle you have to change the rows the class is applied to. If your markup is generated by your content management system then you need to get the server-side code to add that class \u2013 if you have access to that code.\n\n\n\n\nStriping every other row - using classes\n\n\n\n\t\n\t\t\n\t\t\t\n\t\t\t\n\t\t\t\n\t\t\t\n\t\t\n\t\t\n\t\t\t\n\t\t\t\n\t\t\t\n\t\t\t\n\t\t\n\t\t\n\t\t\t\n\t\t\t\n\t\t\t\n\t\t\t\n\t\t\n\t\t\n\t\t\t\n\t\t\t\n\t\t\t\n\t\t\t\n\t\t\n\t\t\n\t\t\t\n\t\t\t\n\t\t\t\n\t\t\t\n\t\t\n\t

Name	Cards sent	Cards received	Cards written but not sent
Ann	40	28	4
Joe	2	27	29
Paul	5	35	2
Louise	65	65	0

\n\n\n\nView Example 1\n\nThis situation is something I deal with on almost every project, and apart from being an extra thing to do, it just isn\u2019t ideal having the server-side code squirt classes into the markup for purely presentational reasons. This is where the nth-child pseudo-class selector comes in. The server-side code creates a valid HTML table for the data, and the CSS then selects the odd rows with the following selector:\n\ntr:nth-child(odd) td {\n\tbackground-color: #86B486;\n}\n\nView Example 2\n\nThe odd and even keywords are very handy in this situation \u2013 however you can also use a multiplier here. 2n would be equivalent to the keyword \u2018odd\u2019 3n would select every third row and so on.\n\nBrowser support\n\nSadly, nth-child has pretty poor browser support. It is not supported in Internet Explorer 8 and has somewhat buggy support in some other browsers. Firefox 3.5 does have support. In some situations however, you might want to consider using JavaScript to add this support to browsers that don\u2019t have it. This can be very useful if you are dealing with a Content Management System where you have no ability to change the server-side code to add classes into the markup.\n\nI\u2019m going to use jQuery in these examples as it is very simple to use the same CSS selector used in the CSS to target elements with jQuery \u2013 however you could use any library or write your own function to do the same job. In the CSS I have added the original class selector to the nth-child selector:\n\ntr:nth-child(odd) td, tr.odd td {\n\tbackground-color: #86B486;\n}\n\nThen I am adding some jQuery to add a class to the markup once the document has loaded \u2013 using the very same nth-child selector that works for browsers that support it. \n\n \n \n\nView Example 3\n\nWe could just add a background colour to the element using jQuery, however I prefer not to mix that information into the JavaScript as if we change the colour on our table rows I would need to remember to change it both in the CSS and in the JavaScript.\n\nDoing something different with the last element\n\nSo here\u2019s another thing that we often deal with. You have a list of items all floated left with a right hand margin on each element constrained within a fixed width layout. If each element has the right margin applied the margin on the final element will cause the set to become too wide forcing that last item down to the next row as shown in the below example where I have used a grey border to indicate the fixed width.\n\n\n\nCurrently we have two ways to deal with this. We can put a negative right margin on the list, the same width as the space between the elements. This means that the extra margin on the final element fills that space and the item doesn\u2019t drop down. \n\n\n\n\nThe last item is different\n\n\n\n\t

\n\t\t

$\"baubles\"$
$\"star\"$
$\"wreath\"$

\n\t

\n\n\n\nView Example 4\n\nThe other solution will be to put a class on the final element and in the CSS remove the margin for this class. \n\nul.gallery li.last {\n\tmargin-right: 0;\n}\n\nThis second solution may not be easy if the content is generated from server-side code that you don\u2019t have access to change.\n\nIt could all be so different. In CSS3 we have marvellously common-sense selectors such as last-child, meaning that we can simply add rules for the last list item. \n\nul.gallery li:last-child {\n\tmargin-right: 0;\n}\n\nView Example 5\n\nThis removed the margin on the li which is the last-child of the ul with a class of gallery. No messing about sticking classes on the last item, or pushing the width of the item out wit a negative margin.\n\nIf this list of items repeated ad infinitum then you could also use nth-child for this task. Creating a rule that makes every 3rd element margin-less.\n\nul.gallery li:nth-child(3n) {\n\tmargin-right: 0;\n}\n\nView Example 6\n\n\n\nA similar example is where the designer has added borders to the bottom of each element \u2013 but the last item does not have a border or is in some other way different. Again, only a class added to the last element will save you here if you cannot rely on using the last-child selector.\n\nBrowser support for last-child\n\nThe situation for last-child is similar to that of nth-child, in that there is no support in Internet Explorer 8. However, once again it is very simple to replicate the functionality using jQuery. Adding our .last class to the last list item.\n\n$(\"ul.gallery li:last-child\").addClass(\"last\");\n\nWe could also use the nth-child selector to add the .last class to every third list item.\n\n$(\"ul.gallery li:nth-child(3n)\").addClass(\"last\");\n\nView Example 7\n\nFun with forms\n\nStyling forms can be a bit of a trial, made difficult by the fact that any CSS applied to the input element will effect text fields, submit buttons, checkboxes and radio buttons. As developers we are left adding classes to our form fields to differentiate them. In most builds all of my text fields have a simple class of text whereas I wouldn\u2019t dream of adding a class of para to every paragraph element in a document.\n\n\n\n\nSyling form fields\n\n\n\n\t

Send your Christmas list to Santa

\n\t\n\n\n\nView Example 8\n\nAttribute selectors provide a way of targeting elements by looking at the attributes of those elements. Unlike the other examples in this article which are CSS3 selectors, the attribute selector is actually a CSS2.1 selector \u2013 it just doesn\u2019t get much use because of lack of support in Internet Explorer 6. Using attribute selectors we can write rules for text inputs and form buttons without needing to add any classes to the markup. For example after removing the text and button classes from my text and submit button input elements I can use the following rules to target them:\n\nform input[type=\"text\"] {\n border: 1px solid #333;\n padding: 0.2em;\n width: 400px;\n}\nform input[type=\"submit\"]{\n border: 1px solid #333;\n background-color: #eee;\n color: #000;\n padding: 0.1em;\n} \n\nView Example 9\n\nAnother problem that I encounter with forms is where I am using CSS to position my labels and form elements by floating the labels. This works fine as long as I want all of my labels to be floated, however sometimes we get a set of radio buttons or a checkbox, and I don\u2019t want the label field to be floated. As you can see in the below example the label for the checkbox is squashed up into the space used for the other labels, yet it makes more sense for the checkbox to display after the text.\n\n\n\nI could use a class on this label element however CSS3 lets me to target the label attribute directly by looking at the value of the for attribute.\n\nlabel[for=\"fOptIn\"] {\n float: none;\n width: auto;\n}\n\n\n\nBeing able to precisely target attributes in this way is incredibly useful, and once IE6 is no longer an issue this will really help to clean up our markup and save us from having to create all kinds of special cases when generating this markup on the server-side.\n\nBrowser support\n\nThe news for attribute selectors is actually pretty good with Internet Explorer 7+, Firefox 2+ and all other modern browsers all having support. As I have already mentioned this is a CSS2.1 selector and so we really should expect to be able to use it as we head into 2010! Internet Explorer 7 has slightly buggy support and will fail on the label example shown above however I discovered a workaround in the Sitepoint CSS reference comments. Adding the selector label[htmlFor=\"fOptIn\"] to the correct selector will create a match for IE7.\n\nIE6 does not support these selector but, once again, you can use jQuery to plug the holes in IE6 support. The following jQuery will add the text and button classes to your fields and also add a checks class to the label for the checkbox, which you can use to remove the float and width for this element.\n\n$('form input[type=\"submit\"]').addClass(\"button\");\n$('form input[type=\"text\"]').addClass(\"text\");\n$('label[for=\"fOptIn\"]').addClass(\"checks\");\n\nView Example 10\n\nThe selectors I\u2019ve used in this article are easy to overlook as we do have ways to achieve these things currently. As developers \u2013 especially when we have frameworks and existing code that cope with these situations \u2013 it is easy to carry on as we always have done. \n\nI think that the time has come to start to clean up our front and backend code and replace our reliance on classes with these more advanced selectors. With the help of a little JavaScript almost all users will still get the full effect and, where we are dealing with purely visual effects, there is definitely a case to be made for not worrying about the very small percentage of people with old browsers and no JavaScript. They will still receive a readable website, it may just be missing some of the finesse offered to the modern browsing experience.", "year": "2009", "author": "Rachel Andrew", "author_slug": "rachelandrew", "published": "2009-12-20T00:00:00+00:00", "url": "https://24ways.org/2009/cleaner-code-with-css3-selectors/", "topic": "code"}