随笔小计 -- - 爱码网

1. <meta http-equiv="mobile-agent" content="format=html5; url=http://m.cnmo.com/">

页头meta声明，当用户用手机访问这个PC端页面时，URL将自动跳转到指定的移动端URL地址。 format设置移动端URL地址网页格式；

2. nofollow 两种用法

1.用于meta元标签：<meta name="robots" content="nofollow" />，告诉爬虫该页面上所有链接都无需追踪。

2.用于a标签：<a href="login.aspx" rel="nofollow">登录</a>,告诉爬虫该页面无需追踪。

3. font-family:"\5FAE\8F6F\96C5\9ED1"

一种unicode编码格式。为了防止在页面中不显示中文的一种兼容写法；相当于 \r\nfont-family:\\“微软雅黑” 或者 \r\nfont-family:\\“Microsoft YaHe”

4. -webkit-appearance:none; -moz-appearance:none;

取消iphone 的自带样式;

只在Chrome、FF浏览器下能用；

5. border-collapse:collapse; 合并边框为一个边框

6. border-spacing:0; 单元格间距

7. box-shadow:inset 0 0 1px #FFF;

所表示的含义是没有偏移，1像素模糊的白色内阴影。

box-shadow还支持多阴影，例如：box-shadow: inset 0 0 1px #fff, inset 4px 4px 20px rgba(255,255,255,0.33), inset -2px -2px 10px rgba(255,255,255,0.25);所表示的含义是，无偏移1像素模糊白色阴影重叠于左上角4像素偏移20像素模糊透明度0.33的白色内阴影再重叠于右下角偏移2像素，模糊10像素，透明度0.25的白色内阴影。

8. background-clip:padding-box;

在写移动端页面时，经常会用padding撑开一个内容，这时如果有圆角的话，里面的背景将超出圆角，看不出圆角效果，这时需要添加这个属性。

9. -webkit-tap-highlight-color ： rgba(0,0,0,0);

这个属性只用于iOS (iPhone和iPad)。当你点击一个链接或者通过Javascript定义的可点击元素的时候，它就会出现一个半透明的灰色背景。要重设这个表现，你可以设置-webkit-tap-highlight-color为任何颜色。

想要禁用这个高亮，设置颜色的alpha值为0即可。

如：设置高亮色为50%透明的红色:

      -webkit-tap-highlight-color: rgba(255,0,0,0.5);

只有iOS(iPhone和iPad)支持

10. display: table-cell;

指让标签元素以表格单元格的形式呈现，类似于td标签

我们都知道，单元格有一些比较特别的属性，例如元素的垂直居中对齐，关联伸缩等，所以display:table-cell还是有不少潜在的使用价值的

　　使用display:table-cell让大小不固定元素垂直居中已经是很老的方法了，

11. 之前一直很纠结 a标签里面可不可以放div，今天看了个门户网站，他们就是这样写的。

<a>

</a>

12. line-height 小于height时，也能实现文字垂直居中

13. transition-duration

让过渡效果持续 5 秒：

   transition-duration: 5s;
   -moz-transition-duration: 5s; /* Firefox 4 */
   -webkit-transition-duration: 5s; /* Safari 和 Chrome */
   -o-transition-duration: 5s; /* Opera */

transition-timing-function

ease：（逐渐变慢）默认值，

linear：（匀速），

ease-in：(加速)，

ease-out：（减速），

ease-in-out：（加速然后减速），

transition-delay

是用来指定一个动画开始执行的时间，也就是说当改变元素属性值后多长时间开始执行transition效果

其取值：<time>为数值，单位为s（秒）或者ms(毫秒)，

14. transform / transform-origin

transform(变形)和transform-origin(变形原点)的说明：

目前这两个属性得到了除去ie以外各个主流浏览器webkit，firefox，opera的支持，属性名分别为 -webkit-transform，-moz-transform，-o-transform;

详情链接 http://blog.sina.com.cn/s/blog_780a942701014xl8.html

15. <html lang="en">

向搜索引擎表示该页面是html语言，并且语言为英文网站，其"lang"的意思就是“language”，语言的意思，而“en”即表示english
你的页面如果是中文页面，可将其改为   
<html lang="zh">  <html lang="zh-cn">
zh即表示中文
这个主要是给搜索引擎看的，搜索引擎不会去判断该站点是中文站还是英文站，所以这句话就是让搜索引擎知道，你的站点是中文站，对html页面本身不会有影响这些现在都是html规范，你的页面越规范，就越容易被收录


16.   clearfix:
  bootstrap 里面的写法：
 .clearfix{
     zoom:1;
 }
 .clear:after,
 .clear:before{
     display:table;
     line-height:0;
     content:"";
 }
 .clear:after{
     clear:both;
 }

因为display: table会产生一些匿名盒子，这些匿名盒子的其中一个（display值为table-cell）会形成Block Formatting Context。

这样我们新的.clearfix就会闭合内部元素的浮动。

17. IE6下实现border的transparent透明解决方案

border:solid 1px transparent;

_border-color:tomato; /*For IE6-*/
_filter:chroma(color=tomato);/*For IE6-*/

原理是先给border定义一个颜色，然后再把这个颜色过滤掉。

(此方法一般不使用)

18. 实现导航条内ul自动居中。在li数量不固定情况下使用。

代码如下：

<div>
     <ul>
         <li>111</li>
         <li>222</li>
         <li>333</li>
         <li>444</li>
         <li>555</li>
    </ul>
</div>    
li{list-style:none;}
div{width:1000px;height:30px;background:#ddd;margin:50px auto; position:relative;}
ul{
   position:relative;
   left:50%;
   float:left;
}
li{
   background:#eee;
   padding:0 20px;
   line-height:30px;
   position:relative;
   right:50%;
   float:left;
}

19. IE6下兼容半透明png图片方法

页面头部插入

<!--[if IE 6]>
    <script type="text/javascript" src="js/DD_belatedPNG.js"></script>
    <script type="text/javascript">DD_belatedPNG.fix('img')</script>
<![endif]-->
img表示标签名

JS文件如下：

/**
* DD_belatedPNG: Adds IE6 support: PNG images for CSS background-image and HTML <IMG/>.
* Author: Drew Diller
* Email: drew.diller@gmail.com
* URL: http://www.dillerdesign.com/experiment/DD_belatedPNG/
* Version: 0.0.8a
* Licensed under the MIT License: http://dillerdesign.com/experiment/DD_belatedPNG/#license
*
* Example usage:
* DD_belatedPNG.fix('.png_bg'); // argument is a CSS selector
* DD_belatedPNG.fixPng( someNode ); // argument is an HTMLDomElement
**/

/*
PLEASE READ:
Absolutely everything in this script is SILLY.  I know this.  IE's rendering of certain pixels doesn't make sense, so neither does this code!
*/

var DD_belatedPNG = {
    ns: 'DD_belatedPNG',
    imgSize: {},
    delay: 10,
    nodesFixed: 0,
    createVmlNameSpace: function () { /* enable VML */
        if (document.namespaces && !document.namespaces[this.ns]) {
            document.namespaces.add(this.ns, 'urn:schemas-microsoft-com:vml');
        }
    },
    createVmlStyleSheet: function () { /* style VML, enable behaviors */
        /*
            Just in case lots of other developers have added
            lots of other stylesheets using document.createStyleSheet
            and hit the 31-limit mark, let's not use that method!
            further reading: http://msdn.microsoft.com/en-us/library/ms531194(VS.85).aspx
        */
        var screenStyleSheet, printStyleSheet;
        screenStyleSheet = document.createElement('style');
        screenStyleSheet.setAttribute('media', 'screen');
        document.documentElement.firstChild.insertBefore(screenStyleSheet, document.documentElement.firstChild.firstChild);
        if (screenStyleSheet.styleSheet) {
            screenStyleSheet = screenStyleSheet.styleSheet;
            screenStyleSheet.addRule(this.ns + '\\:*', '{behavior:url(#default#VML)}');
            screenStyleSheet.addRule(this.ns + '\\:shape', 'position:absolute;');
            screenStyleSheet.addRule('img.' + this.ns + '_sizeFinder', 'behavior:none; border:none; position:absolute; z-index:-1; top:-10000px; visibility:hidden;'); /* large negative top value for avoiding vertical scrollbars for large images, suggested by James O'Brien, http://www.thanatopsic.org/hendrik/ */
            this.screenStyleSheet = screenStyleSheet;
            
            /* Add a print-media stylesheet, for preventing VML artifacts from showing up in print (including preview). */
            /* Thanks to R閙i Pr関ost for automating this! */
            printStyleSheet = document.createElement('style');
            printStyleSheet.setAttribute('media', 'print');
            document.documentElement.firstChild.insertBefore(printStyleSheet, document.documentElement.firstChild.firstChild);
            printStyleSheet = printStyleSheet.styleSheet;
            printStyleSheet.addRule(this.ns + '\\:*', '{display: none !important;}');
            printStyleSheet.addRule('img.' + this.ns + '_sizeFinder', '{display: none !important;}');
        }
    },
    readPropertyChange: function () {
        var el, display, v;
        el = event.srcElement;
        if (!el.vmlInitiated) {
            return;
        }
        if (event.propertyName.search('background') != -1 || event.propertyName.search('border') != -1) {
            DD_belatedPNG.applyVML(el);
        }
        if (event.propertyName == 'style.display') {
            display = (el.currentStyle.display == 'none') ? 'none' : 'block';
            for (v in el.vml) {
                if (el.vml.hasOwnProperty(v)) {
                    el.vml[v].shape.style.display = display;
                }
            }
        }
        if (event.propertyName.search('filter') != -1) {
            DD_belatedPNG.vmlOpacity(el);
        }
    },
    vmlOpacity: function (el) {
        if (el.currentStyle.filter.search('lpha') != -1) {
            var trans = el.currentStyle.filter;
            trans = parseInt(trans.substring(trans.lastIndexOf('=')+1, trans.lastIndexOf(')')), 10)/100;
            el.vml.color.shape.style.filter = el.currentStyle.filter; /* complete guesswork */
            el.vml.image.fill.opacity = trans; /* complete guesswork */
        }
    },
    handlePseudoHover: function (el) {
        setTimeout(function () { /* wouldn't work as intended without setTimeout */
            DD_belatedPNG.applyVML(el);
        }, 1);
    },
    /**
    * This is the method to use in a document.
    * @param {String} selector - REQUIRED - a CSS selector, such as '#doc .container'
    **/
    fix: function (selector) {
        if (this.screenStyleSheet) {
            var selectors, i;
            selectors = selector.split(','); /* multiple selectors supported, no need for multiple calls to this anymore */
            for (i=0; i<selectors.length; i++) {
                this.screenStyleSheet.addRule(selectors[i], 'behavior:expression(DD_belatedPNG.fixPng(this))'); /* seems to execute the function without adding it to the stylesheet - interesting... */
            }
        }
    },
    applyVML: function (el) {
        el.runtimeStyle.cssText = '';
        this.vmlFill(el);
        this.vmlOffsets(el);
        this.vmlOpacity(el);
        if (el.isImg) {
            this.copyImageBorders(el);
        }
    },
    attachHandlers: function (el) {
        var self, handlers, handler, moreForAs, a, h;
        self = this;
        handlers = {resize: 'vmlOffsets', move: 'vmlOffsets'};
        if (el.nodeName == 'A') {
            moreForAs = {mouseleave: 'handlePseudoHover', mouseenter: 'handlePseudoHover', focus: 'handlePseudoHover', blur: 'handlePseudoHover'};
            for (a in moreForAs) {            
                if (moreForAs.hasOwnProperty(a)) {
                    handlers[a] = moreForAs[a];
                }
            }
        }
        for (h in handlers) {
            if (handlers.hasOwnProperty(h)) {
                handler = function () {
                    self[handlers[h]](el);
                };
                el.attachEvent('on' + h, handler);
            }
        }
        el.attachEvent('onpropertychange', this.readPropertyChange);
    },
    giveLayout: function (el) {
        el.style.zoom = 1;
        if (el.currentStyle.position == 'static') {
            el.style.position = 'relative';
        }
    },
    copyImageBorders: function (el) {
        var styles, s;
        styles = {'borderStyle':true, 'borderWidth':true, 'borderColor':true};
        for (s in styles) {
            if (styles.hasOwnProperty(s)) {
                el.vml.color.shape.style[s] = el.currentStyle[s];
            }
        }
    },
    vmlFill: function (el) {
        if (!el.currentStyle) {
            return;
        } else {
            var elStyle, noImg, lib, v, img, imgLoaded;
            elStyle = el.currentStyle;
        }
        for (v in el.vml) {
            if (el.vml.hasOwnProperty(v)) {
                el.vml[v].shape.style.zIndex = elStyle.zIndex;
            }
        }
        el.runtimeStyle.backgroundColor = '';
        el.runtimeStyle.backgroundImage = '';
        noImg = true;
        if (elStyle.backgroundImage != 'none' || el.isImg) {
            if (!el.isImg) {
                el.vmlBg = elStyle.backgroundImage;
                el.vmlBg = el.vmlBg.substr(5, el.vmlBg.lastIndexOf('")')-5);
            }
            else {
                el.vmlBg = el.src;
            }
            lib = this;
            if (!lib.imgSize[el.vmlBg]) { /* determine size of loaded image */
                img = document.createElement('img');
                lib.imgSize[el.vmlBg] = img;
                img.className = lib.ns + '_sizeFinder';
                img.runtimeStyle.cssText = 'behavior:none; position:absolute; left:-10000px; top:-10000px; border:none; margin:0; padding:0;'; /* make sure to set behavior to none to prevent accidental matching of the helper elements! */
                imgLoaded = function () {
                    this.width = this.offsetWidth; /* weird cache-busting requirement! */
                    this.height = this.offsetHeight;
                    lib.vmlOffsets(el);
                };
                img.attachEvent('onload', imgLoaded);
                img.src = el.vmlBg;
                img.removeAttribute('width');
                img.removeAttribute('height');
                document.body.insertBefore(img, document.body.firstChild);
            }
            el.vml.image.fill.src = el.vmlBg;
            noImg = false;
        }
        el.vml.image.fill.on = !noImg;
        el.vml.image.fill.color = 'none';
        el.vml.color.shape.style.backgroundColor = elStyle.backgroundColor;
        el.runtimeStyle.backgroundImage = 'none';
        el.runtimeStyle.backgroundColor = 'transparent';
    },
    /* IE can't figure out what do when the offsetLeft and the clientLeft add up to 1, and the VML ends up getting fuzzy... so we have to push/enlarge things by 1 pixel and then clip off the excess */
    vmlOffsets: function (el) {
        var thisStyle, size, fudge, makeVisible, bg, bgR, dC, altC, b, c, v;
        thisStyle = el.currentStyle;
        size = {'W':el.clientWidth+1, 'H':el.clientHeight+1, 'w':this.imgSize[el.vmlBg].width, 'h':this.imgSize[el.vmlBg].height, 'L':el.offsetLeft, 'T':el.offsetTop, 'bLW':el.clientLeft, 'bTW':el.clientTop};
        fudge = (size.L + size.bLW == 1) ? 1 : 0;
        /* vml shape, left, top, width, height, origin */
        makeVisible = function (vml, l, t, w, h, o) {
            vml.coordsize = w+','+h;
            vml.coordorigin = o+','+o;
            vml.path = 'm0,0l'+w+',0l'+w+','+h+'l0,'+h+' xe';
            vml.style.width = w + 'px';
            vml.style.height = h + 'px';
            vml.style.left = l + 'px';
            vml.style.top = t + 'px';
        };
        makeVisible(el.vml.color.shape, (size.L + (el.isImg ? 0 : size.bLW)), (size.T + (el.isImg ? 0 : size.bTW)), (size.W-1), (size.H-1), 0);
        makeVisible(el.vml.image.shape, (size.L + size.bLW), (size.T + size.bTW), (size.W), (size.H), 1 );
        bg = {'X':0, 'Y':0};
        if (el.isImg) {
            bg.X = parseInt(thisStyle.paddingLeft, 10) + 1;
            bg.Y = parseInt(thisStyle.paddingTop, 10) + 1;
        }
        else {
            for (b in bg) {
                if (bg.hasOwnProperty(b)) {
                    this.figurePercentage(bg, size, b, thisStyle['backgroundPosition'+b]);
                }
            }
        }
        el.vml.image.fill.position = (bg.X/size.W) + ',' + (bg.Y/size.H);
        bgR = thisStyle.backgroundRepeat;
        dC = {'T':1, 'R':size.W+fudge, 'B':size.H, 'L':1+fudge}; /* these are defaults for repeat of any kind */
        altC = { 'X': {'b1': 'L', 'b2': 'R', 'd': 'W'}, 'Y': {'b1': 'T', 'b2': 'B', 'd': 'H'} };
        if (bgR != 'repeat' || el.isImg) {
            c = {'T':(bg.Y), 'R':(bg.X+size.w), 'B':(bg.Y+size.h), 'L':(bg.X)}; /* these are defaults for no-repeat - clips down to the image location */
            if (bgR.search('repeat-') != -1) { /* now let's revert to dC for repeat-x or repeat-y */
                v = bgR.split('repeat-')[1].toUpperCase();
                c[altC[v].b1] = 1;
                c[altC[v].b2] = size[altC[v].d];
            }
            if (c.B > size.H) {
                c.B = size.H;
            }
            el.vml.image.shape.style.clip = 'rect('+c.T+'px '+(c.R+fudge)+'px '+c.B+'px '+(c.L+fudge)+'px)';
        }
        else {
            el.vml.image.shape.style.clip = 'rect('+dC.T+'px '+dC.R+'px '+dC.B+'px '+dC.L+'px)';
        }
    },
    figurePercentage: function (bg, size, axis, position) {
        var horizontal, fraction;
        fraction = true;
        horizontal = (axis == 'X');
        switch(position) {
            case 'left':
            case 'top':
                bg[axis] = 0;
                break;
            case 'center':
                bg[axis] = 0.5;
                break;
            case 'right':
            case 'bottom':
                bg[axis] = 1;
                break;
            default:
                if (position.search('%') != -1) {
                    bg[axis] = parseInt(position, 10) / 100;
                }
                else {
                    fraction = false;
                }
        }
        bg[axis] = Math.ceil(  fraction ? ( (size[horizontal?'W': 'H'] * bg[axis]) - (size[horizontal?'w': 'h'] * bg[axis]) ) : parseInt(position, 10)  );
        if (bg[axis] % 2 === 0) {
            bg[axis]++;
        }
        return bg[axis];
    },
    fixPng: function (el) {
        el.style.behavior = 'none';
        var lib, els, nodeStr, v, e;
        if (el.nodeName == 'BODY' || el.nodeName == 'TD' || el.nodeName == 'TR') { /* elements not supported yet */
            return;
        }
        el.isImg = false;
        if (el.nodeName == 'IMG') {
            if(el.src.toLowerCase().search(/\.png$/) != -1) {
                el.isImg = true;
                el.style.visibility = 'hidden';
            }
            else {
                return;
            }
        }
        else if (el.currentStyle.backgroundImage.toLowerCase().search('.png') == -1) {
            return;
        }
        lib = DD_belatedPNG;
        el.vml = {color: {}, image: {}};
        els = {shape: {}, fill: {}};
        for (v in el.vml) {
            if (el.vml.hasOwnProperty(v)) {
                for (e in els) {
                    if (els.hasOwnProperty(e)) {
                        nodeStr = lib.ns + ':' + e;
                        el.vml[v][e] = document.createElement(nodeStr);
                    }
                }
                el.vml[v].shape.stroked = false;
                el.vml[v].shape.appendChild(el.vml[v].fill);
                el.parentNode.insertBefore(el.vml[v].shape, el);
            }
        }
        el.vml.image.shape.fillcolor = 'none'; /* Don't show blank white shapeangle when waiting for image to load. */
        el.vml.image.fill.type = 'tile'; /* Makes image show up. */
        el.vml.color.fill.on = false; /* Actually going to apply vml element's style.backgroundColor, so hide the whiteness. */
        lib.attachHandlers(el);
        lib.giveLayout(el);
        lib.giveLayout(el.offsetParent);
        el.vmlInitiated = true;
        lib.applyVML(el); /* Render! */
    }
};
try {
    document.execCommand("BackgroundImageCache", false, true); /* TredoSoft Multiple IE doesn't like this, so try{} it */
} catch(r) {}
DD_belatedPNG.createVmlNameSpace();
DD_belatedPNG.createVmlStyleSheet();

View Code

20. background-size：背景图片大小设置

background-size：contain; // 缩小图片来适应元素的尺寸（保持像素的长宽比）；

background-size ：cover; // 扩展图片来填满元素（保持像素的长宽比）；

background-size ：100px 100px; // 调整图片到指定大小；

background-size ：50% 100%; // 调整图片到指定大小，百分比相对于包含元素的尺寸。

IE 和遨游不支持；

Firefox 添加私有属性 -moz-background-size 支持；

Safari 和 Chrome 添加私有属性 -webkit-background-size 支持；

Opera 不支持 background-size 属性，添加其私有属性 -o-background-size 也不支持。

在IE不支持这个属性的时候可以通过滤镜来实现这样的一个效果。

代码如下：

background-image: url('file:///F:/test/images/flashbg.jpg');
background-size: cover;
filter:progid:DXImageTransform.Microsoft.AlphaImageLoader(src='file:///F:/test/images/flashbg.jpg',  sizingMethod='scale');</strong>

这样就可以让IE也实现background-size:100%100%的效果了，注意这两个路径要一样，并且是绝对路径。

21. 解决IE6下fixed固定定位的问题

代码如下：

1 #fixed{
2     position:fixed;
3     _position:absolute;
4     bottom:318px;
5     right:142px;
6     _top:expression(eval(document.documentElement.scrollTop+document.documentElement.clientHeight-this.offsetHeight-(parseInt(this.currentStyle.marginTop,0)||318)-(parseInt(this.currentStyle.marginBottom,10)||0)));
7 }

View Code

22. 浏览器渲染方式小结及窗口各种滚动的详解。

分两种： BackCompat，CSS1Compat 前者是怪异模式，后者是标准模式。

document.compatMode: 可以获取当前浏览器渲染方式

IE默认是BackCompat模式 Gecko内核的浏览器可以看为CSS1Compat标准模式

document.compatMode等于BackCompat时，浏览器客户区宽度是document.body.clientWidth；

document.compatMode等于CSS1Compat时，浏览器客户区宽度是document.documentElement.clientWidth。

浏览器客户区高度、滚动条高度、滚动条的Left、滚动条的Top等等都是上面的情况。

一个准确获取网页客户区的宽高、滚动条宽高、滚动条Left和Top的代码：

if (document.compatMode == \"BackCompat\") {  怪异模式
  cWidth = document.body.clientWidth; 
  cHeight = document.body.clientHeight; 
  sWidth = document.body.scrollWidth; 
  sHeight = document.body.scrollHeight; 
  sLeft = document.body.scrollLeft; 
  sTop = document.body.scrollTop; 
} 
else { //document.compatMode == \"CSS1Compat\"   标准模式
  cWidth = document.documentElement.clientWidth; 
  cHeight = document.documentElement.clientHeight; 
  sWidth = document.documentElement.scrollWidth; 
  sHeight = document.documentElement.scrollHeight; 
  sLeft = document.documentElement.scrollLeft == 0 ? document.body.scrollLeft : document.documentElement.scrollLeft;
sTop = document.documentElement.scrollTop == 0 ? document.body.scrollTop : document.documentElement.scrollTop;
}

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