{"id":4757,"date":"2015-04-19T22:07:21","date_gmt":"2015-04-19T14:07:21","guid":{"rendered":"http:\/\/www.zhangxinxu.com\/wordpress\/?p=4757"},"modified":"2015-04-19T22:08:36","modified_gmt":"2015-04-19T14:08:36","slug":"before-after-pseudo-elements-special-features","status":"publish","type":"post","link":"https:\/\/www.zhangxinxu.com\/wordpress\/2015\/04\/before-after-pseudo-elements-special-features\/","title":{"rendered":"CSS\u4e4bbefore, after\u4f2a\u5143\u7d20\u7279\u6027\u8868\u73b0\u4e24\u5219"},"content":{"rendered":"

by zhangxinxu<\/a> from http:\/\/www.zhangxinxu.com<\/a>
\n\u672c\u6587\u5730\u5740\uff1ahttp:\/\/www.zhangxinxu.com\/wordpress\/?p=4757<\/a><\/p>\n

\u4e00\u3001\u7279\u6027\u8868\u73b0one: \u4e0d\u80fd\u5de6\u53f3:empty\u4f2a\u7c7b<\/h3>\n

CSS3\u9009\u62e9\u5668\u4e2d\u6709\u4e2a:empty<\/code>\u4f2a\u7c7b\uff0c\u8868\u793a\u5f53\u5143\u7d20\u91cc\u9762\u4ec0\u4e48\u90fd\u6ca1\u6709\u7684\u65f6\u5019\uff08\u5305\u62ec\u7a7a\u683c\u3001\u6807\u7b7e\u5185\u6362\u884c\uff09\uff0c\u5e94\u7528\u76f8\u5173\u6837\u5f0f\u3002\u5728\u73b0\u4ee3web\u7f51\u9875\u5f00\u53d1\u5236\u4f5c\u4e2d\uff0c\u975e\u5e38\u5e38\u7528\u4e5f\u975e\u5e38\u65b9\u4fbf\u3002<\/p>\n

\u4f8b\u5982\uff0c\u67d0\u5143\u7d20\u7c7b\u540d\u662f.box<\/code>, \u5982\u4e0bHTML\u548cCSS:<\/p>\n

\n
<div class=\"box\"><\/div><\/pre>\n<\/div>\n
\n
.box { background-color: #cd0000; }\n.box:empty { background-color: #fae6e6; }<\/pre>\n<\/div>\n
\u56e0\u4e3a.box<\/code>\u91cc\u9762\u662f\u7a7a\u5927\u5c41\uff0c\u6240\u4ee5\uff0c\u5448\u73b0\u7684\u80cc\u666f\u8272\u5c31\u4f1a\u662f\u4e0b\u9762\u8fd9\u6837\u5b50\uff1a
\n\"\u6de1\u8272\u80cc\u666f\u6548\u679c\"<\/p>\n
\u5047\u5982.box<\/code>\u91cc\u9762\u6709\u7a7a\u683c\uff0c\u6216\u662f\u6587\u5b57\uff0c\u6216\u662f\u6807\u7b7e\u4e4b\u7c7b\uff1a<\/p>\n
\n
<div class=\"box\">\u6211\u662f\u6587\u5b57<\/div><\/pre>\n<\/div>\n
\u5219\uff0c:empty<\/code>\u5931\u6548\uff0c\u4e8e\u662f\uff0c\u5448\u73b0\u7684\u662f\u9753\u4e3d\u7684\u7ea2\u8272\uff1a
\n\"\u5927\u7ea2\u80cc\u666f\u8272\"<\/p>\n
\u4e0b\u9762\uff0c\u9ad8\u80fd\u6765\u4e86\uff0c\u8bf7\u95ee\uff0c\u5982\u679c\u6211\u4eec\u4f7f\u7528before<\/code>\u6216after<\/code>\u4f2a\u5143\u7d20\u5728.box<\/code>\u91cc\u9762\u751f\u6210\u5185\u5bb9\uff0c:empty<\/code>\u4f2a\u7c7b\u8fd8\u6709\u4f5c\u7528\u5417\uff1f<\/p>\n
\u8fd9\u4e2a\u95ee\u9898\u52a8\u52a8\u811a\u8dbe\u5934\u60f3\u60f3\u90fd\u77e5\u9053:empty<\/code>\u4f2a\u7c7b\u4f9d\u7136\u662f\u8d77\u4f5c\u7528\u7684\u2026\u2026\u2026\u2026\u2026\u2026\u624d\u2122\u602a\u5462\uff01\u4f60\u7684\u811a\u8dbe\u5934\u662f\u957f\u8111\u888b\u4e0a\u7684\u5427\uff01\u8fd9\u4e48\u6709\u5b66\u95ee\u7684\u95ee\u9898\uff0c\u54b1\u5c31\u4e0d\u8981\u60f3\u5f53\u7136YY\u4e86\uff0c\u5199\u4e2a\u7b80\u6613Demo\uff0c\u5b9e\u8df5\u4e00\u4e0b\uff0c\u81ea\u7136\u51fa\u771f\u77e5\uff01<\/p>\n
\u4e56\uff0c\u8bf7\u72e0\u72e0\u5730\u70b9\u51fb\u8fd9\u91cc\uff1a:empty\u4f2a\u7c7b\u548cbefore\/after\u4f2a\u5143\u7d20Demo<\/a><\/p>\n
\u524d\u97623\u4e2a\u6846\u6846\u662f\u8ba9\u4f60\u719f\u6089:empty<\/code>\u4f2a\u7c7b\u7684\uff0c\u54b1\u4eec\u76ee\u5149\u76f4\u63a5\u843d\u5230\u7b2c\u56db\u4e2a\u65b9\u5757\uff0c\u91cc\u9762\u7684\u6587\u5b57\u5c31\u662f\u4f2a\u5143\u7d20\u751f\u6210\u7684\uff1a<\/p>\n
\n
.pseudo::after { content: '\u4f2a\u5143\u7d20\u751f\u6210\u5185\u5bb9'; }<\/pre>\n<\/div>\n
\u7ed3\u679c\uff0c\u6240\u6709\u73b0\u4ee3\u6d4f\u89c8\u5668\u4e0b\u9762\uff0c\u4f9d\u7136\u662f\u5a18\u70ae\u7ea2\u80cc\u666f\u8272\uff0c\u622a\u56fe\u5982\u4e0b\uff1a
\n\"\u6de1\u8272\u80cc\u666f\"<\/p>\n
\u6b64\u8868\u73b0\u8bf4\u660e\uff0c\u7a7a\u5143\u7d20\u5185\u90e8\u4f7f\u7528\u4f2a\u5143\u7d20\u751f\u6210\u7684\u5185\u5bb9\uff0c\u662f\u4e0d\u88ab:empty<\/code>\u4f2a\u7c7b\u8ba4\u53ef\u7684\uff0c\u9009\u62e9\u5668\u4f9d\u7136\u8ba4\u4e3a\u8fd9\u662f\u4e2a\u7a7a\u5143\u7d20\u3002<\/p>\n
\u5176\u5b9e\u5462\uff0c\u6211\u4eec\u9a6c\u540e\u70ae\u4e00\u4e0b\uff0c::before<\/code>, ::after<\/code>\u7684\u540d\u79f0\u5176\u5b9e\u5c31\u51fa\u5356\u4e86\u81ea\u5df1\uff0c\u5bf9\u5427\uff0c\u6211\u4eec\u5e73\u5e38\u90fd\u5728\u5462\u4e48\u79f0\u547c\u7684\uff1f\u201c\u4f2a\u5143\u7d20\u201d\u554a\uff0c\u5176\u4e2d\u5927\u5927\u7684\u7684\u201c\u4f2a\u201d\u5b57\u5c31\u8868\u660e\u8ddf\u4e00\u822c\u7684\u5143\u7d20\u4e0d\u4e00\u6837\u3002<\/p>\n
\u8fd9\u4e0d\uff0c\u8fd9\u91cc\u88ab:empty<\/code>\u4f2a\u7c7b\u7ed9\u6392\u6324\u4e86\u3002<\/p>\n
\u4e8c\u3001\u7279\u6027\u8868\u73b0two: content\u52a8\u6001\u5448\u73b0\u503c\u65e0\u6cd5\u83b7\u53d6<\/h3>\n
\u5bf9\u4f2a\u5143\u7d20\u719f\u6089\u7684\u540c\u5b66\u5e94\u8be5\u90fd\u77e5\u9053\uff0ccontent\u5185\u5bb9\u52a8\u6001\u751f\u6210\u6280\u672f<\/a>\u53ef\u4ee5\u52a8\u6001\u663e\u793a\u5404\u79cd\u5185\u5bb9\uff0c\u5305\u62ec\u5c5e\u6027\u503c\u3001\u8ba1\u6570\u5668<\/a>\u7b49\uff0c\u4f46\u662f\uff0c\u4f60\u53ef\u80fd\u4e0d\u77e5\u9053\u7684\u662f\uff0c\u6211\u4eec\u76ee\u524d\u538b\u6839\u6ca1\u6709\u529e\u6cd5\u83b7\u5f97\u8fd9\u4e9b\u6700\u7ec8\u5177\u4f53\u5448\u73b0\u7684content<\/code>\u5185\u5bb9\uff0c\u4e3a\u4ec0\u4e48\u5462\uff1f\u56e0\u4e3a\u6211\u4eec\u662f\u98de\u5929\u5c0f\u5973\u8b66\uff0c\u6211\u5478~\u4e0d\u5bf9\uff0c\u56e0\u4e3a\u6211\u4eec\u662f\u4f2a\u5143\u7d20\u3002<\/p>\n
\u9996\u5148\uff0c\u4e3a\u907f\u514d\u6b67\u4e49\uff0c\u6211\u6709\u5fc5\u8981\u89e3\u91ca\u6e05\u695a\uff0c\u6211\u4eec\u4e0d\u662f\u6ca1\u6cd5\u83b7\u5f97CSS\u4e2dcontent<\/code>\u7684\u5c5e\u6027\u503c\uff0c\u800c\u662f\u6ca1\u6cd5\u83b7\u5f97\u9875\u9762\u4e0acontent<\/code>\u6700\u7ec8\u5448\u73b0\u7684\u5185\u5bb9\u503c\u3002\u6709\u5565\u533a\u522b\u5462\uff0c\u4e3e\u4e2a\u4f8b\u5b50\u5927\u5bb6\u5e94\u8be5\u5c31\u6e05\u695a\u4e86\uff01<\/p>\n
\u60a8\u53ef\u4ee5\u72e0\u72e0\u5730\u70b9\u51fb\u8fd9\u91cc\uff1aCSS\u4f2a\u7c7b\u8ba1\u6570\u5668\u52a8\u6001\u83b7\u5f97\u9009\u4e2d\u5143\u7d20\u4e2a\u6570Demo<\/a><\/p>\n
\u4e0a\u9762\u8fd9\u4e2aDemo\u662f\u53bb\u5e74\u201cCSS\u8ba1\u6570\u5668+\u4f2a\u7c7b\u5b9e\u73b0\u6570\u503c\u52a8\u6001\u8ba1\u7b97\u4e0e\u5448\u73b0<\/a>\u201d\u4e00\u6587\u4e2d\u4f7f\u7528\u8fc7\u7684Demo\uff0c\u5bf9\uff0c\u5c31\u662f\u540c\u4e00\u4e2a\u3002<\/p>\n
\u4f7f\u7528\u7eafCSS\u52a8\u6001\u663e\u793a\u4f60\u5f53\u524d\u9009\u62e9\u4e86\u51e0\u9879\u5185\u5bb9\uff1a
\n\"CSS\u8ba1\u6570\u5668\u4e0e\u6570\u503c\u52a8\u6001\u53d8\u5316\"<\/p>\n
\u4f2a\u5143\u7d20\u76f8\u5173CSS\u5982\u4e0b\uff1a<\/p>\n
\n
.total::after {\n  content: counter(icecream);\n}<\/pre>\n<\/div>\n
\u5f88\u7b80\u5355\u7684CSS\uff0c\u4f2a\u5143\u7d20\uff0c\u5185\u5bb9\u663e\u793a\u7684\u662ficecream<\/code>\u8fd9\u4e2a\u8ba1\u6570\u5668\u5f53\u524d\u7684\u503c\uff1f<\/p>\n
\u9ad8\u80fd\u518d\u6b21\u6765\u4e34\uff0c\u5982\u679c\u8ba9\u4f60\u83b7\u5f97.total<\/code>\u8fd9\u4e2a\u5143\u7d20\u76ee\u524d\u5448\u73b0\u7684\u6570\u503c\u6570\u76ee(\u6bd4\u65b9\u8bf4\u4e0a\u9762\u622a\u56fe\u663e\u793a\u76843<\/code>)\uff0c\u4f60\u600e\u4e48\u83b7\u53d6\uff1f<\/p>\n
\u544a\u8bc9\u4f60\uff0c\u4f60\u5984\u56fe\u60f3\u901a\u8fc7.total<\/code>\u8fd9\u4e2a\u5143\u7d20\u83b7\u5f97\u8fd9\u4e2a\u52a8\u6001\u6570\u503c3<\/code>\u96be\u4e8e\u4e0a\u9752\u5929\uff01<\/p>\n
\u4ee5\u524d\u4ecb\u7ecd\u8fc7window.getComputedStyle\u65b9\u6cd5<\/a>\uff0c\u53ef\u4ee5\u83b7\u5f97\u4f2a\u5143\u7d20\u7684\u8ba1\u7b97\u6837\u5f0f\u3002\u4f46\u662f\uff0c\u62b1\u6b49\uff0c\u5f97\u5230\u7684\u53ea\u662f\u7eaf\u7cb9\u7684content<\/code>\u5728CSS\u6587\u4ef6\u4e2d\u7684\u5c5e\u6027\u503c\uff0c\u4f8b\u5982\u8fd9\u91cc\uff1a<\/p>\n
\n
var dom = document.querySelector(\".total\"),\nwindow.getComputedStyle(dom , \"::after\").content;   \/\/ \u7ed3\u679c\u662f\uff1a\"counter(icecream)\"<\/span><\/pre>\n<\/div>\n
\u7ed3\u679c\u662f”counter(icecream)”\uff0c\u800c\u4e0d\u662f\u6570\u503c3<\/code>\u3002\u4e3a\u5565\u5b50\u6ca1\u6cd5\u83b7\u53d6\u5462\uff1f\u6211\u4eec\u7ee7\u7eed\u9a6c\u540e\u70ae\u4e00\u4e0b\uff0c\u56e0\u4e3a\u662f\u201c\u4f2a\u5143\u7d20\u201d\uff0c\u4e0d\u662f\u5143\u7d20\u3002\u54c8\u54c8\uff0c\u8fd9\u4e2a\u89e3\u91ca\u597d\u50cf\u6709\u70b9\u6577\u884d\uff0c\u6211\u7279\u610f\u53bb\u89c4\u8303\u6587\u6863<\/a>\u770b\u4e86\u4e00\u5708\uff0c\u6ca1\u627e\u5230\u5f88\u660e\u786e\u7684\u89e3\u91ca\u3002\u4e0d\u8fc7\u7f51\u4e0a\u6709\u8bf4\u6cd5\u662f\u56e0\u4e3abefore<\/code>, after<\/code>\u4e0d\u5c5e\u4e8e\u6b63\u5e38DOM\u6811\u8282\u70b9\uff0c\u56e0\u6b64\uff0c\u5c31\u6ca1\u6cd5\u5f97\u5230\u52a8\u6001\u5448\u73b0\u5185\u5bb9\u3002<\/p>\n
\u4e09\u3001\u7ed3\u675f\u8bed<\/h3>\n
\u5173\u4e8e\u4ee5\u4e0abefore<\/code>, after<\/code>\u4f2a\u5143\u7d20\u4e24\u4e2a\u89e3\u91ca\uff0c\u8fd8\u671b\u5bf9\u89c4\u8303\u5bf9\u6807\u51c6\u6709\u8fc7\u7814\u7a76\u7684\u540c\u884c\u6307\u70b9\u4e0b\uff0c\u4e5f\u5c31\u662f\u4ece\u6839\u672c\u4e0a\u89e3\u91ca\u4e0b\u539f\u56e0\u3002<\/p>\n
\u597d\u4e86\uff0c\u672c\u6587\u7684\u5185\u5bb9\u5c31\u8fd9\u4e9b\uff0c\u6b22\u8fce\u4ea4\u6d41\uff0c\u6b22\u8fce\u53cd\u9988\u3002\u884c\u4e3a\u4ed3\u4fc3\uff0c\u9519\u8bef\u96be\u514d\uff0c\u6b22\u8fce\u7ea0\u6b63\uff0c\u611f\u8c22\u9605\u8bfb\uff01<\/p>\n
 <\/p>\n
\u672c\u6587\u4e3a\u539f\u521b\u6587\u7ae0\uff0c\u5305\u542b\u811a\u672c\u884c\u4e3a\uff0c\u4f1a\u7ecf\u5e38\u66f4\u65b0\u77e5\u8bc6\u70b9\u4ee5\u53ca\u4fee\u6b63\u4e00\u4e9b\u9519\u8bef\uff0c\u56e0\u6b64\u8f6c\u8f7d\u8bf7\u4fdd\u7559\u539f\u51fa\u5904\uff0c\u65b9\u4fbf\u6eaf\u6e90\uff0c\u907f\u514d\u9648\u65e7\u9519\u8bef\u77e5\u8bc6\u7684\u8bef\u5bfc\uff0c\u540c\u65f6\u6709\u66f4\u597d\u7684\u9605\u8bfb\u4f53\u9a8c\u3002
\n\u672c\u6587\u5730\u5740\uff1ahttp:\/\/www.zhangxinxu.com\/wordpress\/?p=4757<\/a><\/p>\n
\uff08\u672c\u7bc7\u5b8c\uff09<\/p>\n","protected":false},"excerpt":{"rendered":"
\u4f2a\u5143\u7d20\u4e4b\u6240\u4ee5\u79f0\u4e4b\u4e3a\u201c\u4f2a\u5143\u7d20\u201d\u4e00\u5b9a\u662f\u6709\u5176\u539f\u56e0\u7684\uff0c\u672c\u6587\u5c31\u4e3e\u4e24\u4e2a\u7279\u5f81\u4f8b\u5b50\uff0c\u5c55\u793a\u4e0b\u4f2a\u5143\u7d20\u8ddf\u666e\u901a\u5143\u7d20\uff0c\u5230\u5e95\u6709\u54ea\u4e9b\u4e0d\u4e00\u6837\u7684\u5730\u65b9\u3002<\/p>\n
\u4f9d\u7136\uff0c\u6709Demo\u3001\u6709\u622a\u56fe\uff0c\u6709\u6e90\u4ee3\u7801\u5c55\u793a\u3002\u603b\u4e4b\uff0c\u5e0c\u671b\u672c\u6587\u7684\u5185\u5bb9\u80fd\u591f\u5bf9\u60a8\u7684\u5b66\u4e60\u6709\u6240\u5e2e\u52a9\u3002<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[3],"tags":[319,366,824,365,938,936,823],"_links":{"self":[{"href":"https:\/\/www.zhangxinxu.com\/wordpress\/wp-json\/wp\/v2\/posts\/4757"}],"collection":[{"href":"https:\/\/www.zhangxinxu.com\/wordpress\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.zhangxinxu.com\/wordpress\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.zhangxinxu.com\/wordpress\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.zhangxinxu.com\/wordpress\/wp-json\/wp\/v2\/comments?post=4757"}],"version-history":[{"count":0,"href":"https:\/\/www.zhangxinxu.com\/wordpress\/wp-json\/wp\/v2\/posts\/4757\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.zhangxinxu.com\/wordpress\/wp-json\/wp\/v2\/media?parent=4757"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.zhangxinxu.com\/wordpress\/wp-json\/wp\/v2\/categories?post=4757"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.zhangxinxu.com\/wordpress\/wp-json\/wp\/v2\/tags?post=4757"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}