示例:data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAE4AAAB6CAYAAAARQWWmAAAAAXNSR0IArs4c6QAAAARnQU1BAACxjwv8YQUAAAAJcEhZcwAADsMAAA7DAcdvqGQAAA2+SURBVHhe7Z1pU1zHFYbzC5NUkkrlQyqpOOW44iSO5ZTjihPHURLHcizH5U02GEmAWIUQIEAgAUJIiFULCLRvSEJCbFrYEcvJPM0c6OnpO6AxIJi5b9VbZujTfbofernXmjvzPQmVlEJwSSoEl6Q2DNzi4uKGeKtoXcH5BrqRfplaN3C+geGFhYV1sa9t/LL0ncG5A7EHOz8/7/Xc3FxC++pgu20372YraXBux11YNojnz5/HeHZ2NqHdeLstF6Lbj81SUuDsjvqA6YCBMDMzYzw9PR3nqampGPtitL4NdDWAm6EXBmd30IamwBSWDhwgk5OTMjExsezx8fGEtmOpa0O1ISrAlwEvaXA+aAqMgSqgsbExefbsmTx9+lSePHli/Pjx44TWOOpQlzYUqEIkVyJ4G60XAhcETWeZAjt79qzXQfLF4iApQJ19LwNe0uB80JgVzBAfBBwkXywOEjnIFQRvS4HzQdPlqdBYWqOjo14I2NXU1IwMDY1KU1OztLa2rxqvIge5bHjust1oeGsCp52wwfmgjYyMyKNHj+IAqFULC4ty4mS7fPbVgRgXl1RJZ2d8vCtykMsHzwWHN0IvBM6ebSwPNmn2G5YOs4AB9ff3x8CyrWpt75LP9+RF/tsdOTWnIrOtTQ6X15rfHS6viYt3RQ5ykZPc9IG+bOaSTQqcPds48TgJh4aG5MGDB3Lnzp0YWLa1ra++KZD6xlbzGml5UUmlfPl1fmTWdS7H+0QOcpGT3PQh0azbCK0KTpNjOqN7m842XaIDAwNy9+5duXHjRrRmvIDR3tFhlmVd/cllYKrbd+6bsidPx8xrLXdNDnKRU5eszjr6Rh9tcHi99ULg3GXK/sL1Fn95ls+tW7fk8uXL0ZrxYtDt7UvgTjSeWgah6n/wyJQNjzw2r7XcNTnIRU5y0wf64i5Xu+/rrTWD02VKp+xlqnsbM+D69ety8eLFaM14Mej1AEcOcpFT9zp7uSq4jVyuLwxO9zduhdiYWSoPHz40+86VK1fkwoUL0ZrxYtDrAY4c5CInuekDfaFPm7XPJQXO3t+Gh4eXl+mlS5fMwIJE2XqAw+TS5Uof3H1uS4PT/e3+/ftmw+7p6ZGOyObvan5+QeoaWqSlpW3Nh8P4+KQ5Ze3rOjU5yEVOcus+t63ADQ4Oyr1798ye093dLW1tbXEDBRaXGWdaL5i21nI5UlpWY+JmI/lckYNc5CQ3fdjS4NwTlWsoNmc6f+3aNenq6opczLbGQFPnFZbL/gNlps21XABn7C2WqpqTJt4VOchFTnLTB/rinqxbHhynG4Ng025paYmDhlmaLMPmlnOmrUS3XKVlR83rO3390V7EihzkIqeerNsCHMe+C+7q1atmMGfOnPGCw0ADCDONfc+9yQcaM48Y4AWJHOQipwuOvqUcOMTexpLMziuXlrYuuXTlphytbTDAMrKKTBl7ncb7lBLguO3p6+szgzh//vyq4NDDgSEpOby0p+ky5ef9uYek8WRzXLwrcpCLnOSmD9seXHNzc7RmvGyIuC1yTbcv51Bkhh2V6ZnZaNSK3Hg1OdIaHM4+UCql5cejEbHyxeMQXMQhuCTBVdfUS+9l//+K8sXjEFzUQfLF4hBc1EHyxeKUBecbLA6SLxYHKQQXlS8WByntwT0dX5Sb9xak8livNDVfWDVelbbgIrepsqd4Rr7/xliMd355Xzo6z8XFu0pbcPnVs/KDP45L/tFZefxsUU6e7pLde/vM73Zn9cXFu0pLcIzhx2+NyxeFM+Y10vL3v+iXH+0Yk46OpVkXpJQFFyRgtLSdN8uyoPzaMjBVe8+8KXs4FFnLEWm567QEx/8+B05p9eVlEKqeG0vgbveH4GLEoENwIbjECsH5tSngns+JfJY/LSdOda/5cBh+smhO2faO8zHQcMqCcwfa0nbBXGbkVs5G2lrb5ch/v71r4qZWwpaVNuDwn3cPyKs7Jwy41S6A+deuX/71sfwnazrai1ilFbjCiqtmGe4vn5G5+cS3XLsy7prXnZcigR6lFTgMNIAw09j33Jt89jNmHjHAC1LagaP/7G0syd/8c0IOVM3K8bY5+bb4pnycdVd+8e6oKWOvY7kGKe3Aqa7cnpd3Pp00kHSZ8vPv/jUo5bXxlymuUhZckGyI+HRLl7y2c0R2fDwlY5PRIEtuvDrtweE/fDAo734+FY2IlS8eh+AiDsElCS6z8IYca4l/8yDyxeMQXNRB8sXiEFzUQfLF4pQF5xssDpIvFgcpBBeVLxYHKQQXlS8WByltwV2/0ScVlQ3m7V2Yt3rhA/llcux4Y1y8q7QEd79/wLx1Na+wMg7ct/sOmre0NpxYeuomSGkHbm5u3jzrkFtwxLzrXKXl3NhnRuDxjAMPlQQpZcHZ4vms2uPNZmbpjLLfII1tPRwYNjEHInCZhQVFR2Ke+8IpDw5oQMjce9CAy3X2MLWrm7fuSUXVCQNuT0aBacOGl/LgmGlAY4kiGxbPa1VW15kZRVx3zzWTwxZxHR2dBh5xWjflwenmr9KB8xRN1v4Sc0hkRvaz3PwK83N+UVWk7fh/xNHDQ1+nLbj8ogr58pv8yOnZZF4jTts9mYVSXdtkXiOND8FFBs1pyZ5VVlG7DELV3nnRlOmjllqeNuCCBowGh0bNsrSfDNTy43VLTxiebFpqQ+X+AdISHLOJWcXsUmk5s9CURWalxqMQXFTsY+xn7GuIMvY79j32Pzc+BBcVJycnKMuSE5WTlZ85ae0Pp1KF4CzRHtduXMNxjcY1nX40kBufduC4U9ibfSgOhCstd60qPHhUyisboq9SGJyqraPbLMGz53vN7Re3TT5T5jNlFZXHTBv25UvKg+NW63BFvRn4d3FOXpm59UobcCo+gEVnkM/uTFNT1nwm/uM40gacygWgDpIvFofgog6SLxaH4KIOki8Wpyw432BxkHyxOEghuKh8sThIIbiofLE4SGkL7tS5OfnH11Pm7V2Yt3rhtz56JDmHrsfFu0pLcN3Xlh4C+f2Hk3Hgfv33EfOW1kNVS29nDVLageNTgHjW4fUPJsy7zlVazrvOX3lvxDzjwBM4QUpZcLZ4Pmt3zrSZWa+8Nyo/fHM85g3S2NaVOwsm5vUPJpferfnpg5jnvnDKgwMaS+/nfxk34N76aEDyDl+NgYBdtXbPyc5vlpbwz95+Ytqw4aU8OGYa0PSDumxY7R3n5Ov8m2ZGEVd9+rl54sYWca2RJQs84rRuyoPTzV+lA+cpmlffHzGHxK/+NiK//feE+fmNXZPmaRuVxuvhoa/TFtw7nwzIT/70TEoqV05PTtufvj0uH+5defBN40NwkUHzCCZ71v/2rXwKv6qodumpQv3HfC1PG3BBA0Y89May7Oxd2dC0vKB86QlDHorTeOT+AdISHLOJWcXsUmk5s5AyZqXGoxBcVOxj7Gfsa4gy9jv2PfY/Nz4EFxUnJycoy5ITlZOVnzlp7Q+nUqUFOPvjbIPAIa7ZuHYzdxWRazSu6bi201g73gWXEh9nm+gDlHfseiSv7RyOA+FKy12rdnw8Ke/viQWXkp88rSo4OmuW4KG6WXP7xW2Tz5T5TNln2bdNG5/sXfmUr20LbrUPiVdxq/XeV1Nm4N/Fb+4aNLdeCm7bfki8C879WgJXD4YWl2eQz+5MU1N2vLFnGZh6230twVq/CCNILgB1kHyxeNt9EYYP3Fq+ekXlg4CD5IvF2/6rV5L5sh+fg+SLVW/LL/tZ7eul2IMaGxulpqZGysvL5eDBg5Kfny85OTmyb98+ycrKkszMTMnIyIgxv6OMGGKpQ13aoC3apG1ybLuvl2LTpXMc+0FfaMYbBE+fPi319fVSXV1tBl5SUiKFhYWSl5cnubm5Bkx2dnaM+R1lxBBLHerSBm3RJm1vqy80wwrOPll1n9PlytfbMSPYwE+dOmUGzGyprKyUsrIyKS0tNUCKi4ulqKgoxvyOMmKIpQ51aYO2aJO2t9VX6GH+gnTK3edYKtz2MAPYsHt7e80tEQNllrDE6urqpLa21syeqqoqA+XIkSMx5neUEUMsdahLG7RFm7RNDnKRk9zu/kYf7dmG11urgkM2OP6Sus/pcuUair+8fk0oy4gBMjtYWuxLDL6pqcmAaGhoMLMIMLb5HWXEEEsd6tIGbdEmbZNjy39NKHLB2cuVvzQbs+51LB8GxqxgSbEfMWhOQi4jmDnA4OqfWyfb/I4yYoilDnVpg7Zok7bJoXsbuXW22ct0S4Gz4dmzjv1FlywDYjawlNiHmCGcgFw+cO3FhStX/RgotvX3xBBLHerSBm3RJm2TQ5couRPNNrwRWhM45ILTvc6FxyxgCbH/MDMYLLOEgTNjgMCtEuYm3bb+nhhiqUNd2qAt2qRtcvigbdZsQ2sGh3zwWB42PJYO+w4zgkEyO7jWYuBc5XOLhIHhs5YTSx3q0gZt0SZtk8OGtplLVJU0uCB47Dds1swILhOYHQyYq3sGz30lIBKZGGKpQ13aoC3apG1yBEHbkuBQEDxdtmzSCpBZwUCZIQoSM2sSWeOoQ13aoC0FRg5yuctzs6ChpMEFwdPZx+AUIrdCDFoNhES2Y6mrsBQYORJBwxutFwaH7A7a8GyANkQbpG2A2PbFaH2FZQN7WdBQUuCQ3VHsA6jWAauBkMhuvN1WImB4s5Q0OJXbcR2QDdG1DcJnXx1st+3m3VyJ/B/HAA8KyZnKwgAAAABJRU5ErkJggg==
4.利用缓存
设置缓存来减少不必要的网络要求。强缓存/协商缓存
5.gzip压缩gzip压缩实质上是一种做事器编码,客户端解码的过程
开启gzip压缩后的要求流程
1.浏览器要求做事器时头信息Accept-Encoding: gzip, deflate来见告做事器,浏览器支持gzip压缩2.做事器收到要求后,师长西席成response,然后通过gzip对response进行编码,并增加Content-Encoding:gzip头信息返回给客户端3.客户端收到response后,根据gzip进行解码。6.css引入位置(图片来自网络侵删)将css的引入写在head标签内
只管浏览器没有限定css的引入位置,但是css写在head内可以加快css的加载,避免页面不必要的重绘,css加载会壅塞后续js的实行以及dom树的渲染,以是引入最好位置便是head内js代码之前。
7.避免利用css表达式expression
示例:background-color:expression((newDate()).getHours()%2?"#B8D4FF":"#F08A00");
每当鼠标移动或者滚动,都会触揭橥达式,这样会拖慢页面其他脚本实行效率,影响体验。
8.js/css利用外部引入将不常用的js或css利用外部引用,利用缓存来加快页面访问速率(干系参考强缓存、协商缓存)。
9.资源压缩js、css删减注释,压缩,减小js、css体积,加快加载速率。
10.开启持久连接每个连接可以处理多个要求-相应事务
非持久连接,当相应完毕后,当前连接会关闭,当开启持久连接后,当前连接在接管相应后还可以连续要求。
http开启keepalive,复用http要求,避免频繁建立http要求
11.不要过度利用postpost要求浏览器分为两步 1.发送头数据head2.发送要求体。get要求只发送一个tcp数据包13.掌握页面dom数量当页面解析渲染时,须要将html构建为dom树,解析css天生CSSOM树,将DOM与CSSOM合并天生渲染树,当dom数量过多时会影响dom解析以及终极的渲染韶光,以是减少dom数量可以加速页面的渲染韶光。
掌握台查看dom数量:document.getElementsByTagName('').length
14.掌握cookie减少cookie大小,cookie会随每次要求提交到做事器,也会随相应返回到客户端,cookie会影响要求跟相应数据包大小。
15.利用事宜代理事宜代理又被称为事宜委托,是事宜绑定中的一个常用技巧,便是把绑定在子元素上的相应事宜委托给父元素,减少事宜注册。事理为DOM的事宜冒泡,利用事宜代理,由父组件代理子组件事宜。
事宜传播:
捕获阶段 从window工具到目标阶段,称之为捕获阶段。目标阶段 事宜在目标上冒泡阶段 从目标阶段一层层向上通报称之为冒泡阶段。16.不要给img标签的src设置为空老版本浏览器如果检测到src为空,还是会向做事器发送要求,如果想要利用图片
图片客户端图片设置默认src为默认图客户端要求做事器,获取图片列表客户端拿到图片列表后将图片地址赋值给img标签的自定义属性,例如data-src监听图片是否在可视范围,如果图片在可视范围,则把图片的data-src赋值给srcimg根据src要求做事器获取图片资源