需求缘由

项目是前后端不分离开发的，很老的项目，里面很多插件只能支持ie8，业主公司浏览器都是ie8 ，这次想给所有页面添加用户水印，所以开发需要兼容ie8

水印代码

创建一个js 文件watermark.js

// 水印
// 水印
(function(watermark){
    window.watermarkdivs = [];
    // 加载水印
    var loadMark = function(settings) {
        var defaultSettings={
            watermark_txt:watermark.watermark_txt, //水印内容
            watermark_x:20,//水印起始位置x轴坐标
            watermark_y:20,//水印起始位置Y轴坐标
            watermark_rows:0,//水印行数
            watermark_cols:0,//水印列数
            watermark_x_space:200,//水印x轴间隔
            watermark_y_space:100,//水印y轴间隔
            watermark_font:'微软雅黑',//水印字体
            watermark_color:'black',//水印字体颜色
            watermark_fontsize:'28px',//水印字体大小
            watermark_alpha:0.15,//水印透明度，要求设置在大于等于0.003
            watermark_width:150,//水印宽度
            watermark_height:100,//水印长度
            watermark_angle:15,//水印倾斜度数
            watermark_progid:'alpha(opacity=15)'

        };
        //采用配置项替换默认值，作用类似jquery.extend
        if(arguments.length===1&&typeof arguments[0] ==="object" )
        {
            var src=arguments[0]||{};
            for(key in src)
            {
                if(src[key]&&defaultSettings[key]&&src[key]===defaultSettings[key])
                    continue;
                else if(src[key])
                    defaultSettings[key]=src[key];
            }
        }

        if (window.watermarkdivs && window.watermarkdivs.length > 0) {
            document.body.removeChild(document.getElementById("markid"));
            window.watermarkdivs = [];
        }

        //获取页面最大宽度
        var page_width = Math.max(document.body.scrollWidth,document.body.clientWidth);
        //获取页面最大长度
        var page_height = Math.max(document.body.scrollHeight,document.body.clientHeight);

        // 创建文档碎片
        var oTemp = document.createDocumentFragment();
        //创建水印外壳div
        var watermarkDiv = document.getElementById("markid");

        if(!watermarkDiv){
            watermarkDiv =document.createElement('div');
            watermarkDiv.id="markid";
            watermarkDiv.style.pointerEvents = "none";
            document.body.appendChild(watermarkDiv);
        }

        //如果将水印列数设置为0，或水印列数设置过大，超过页面最大宽度，则重新计算水印列数和水印x轴间隔
        if (defaultSettings.watermark_cols == 0 || (parseInt(defaultSettings.watermark_x + defaultSettings.watermark_width *defaultSettings.watermark_cols + defaultSettings.watermark_x_space * (defaultSettings.watermark_cols - 1)) > page_width)) {
            defaultSettings.watermark_cols = parseInt((page_width - defaultSettings.watermark_x + defaultSettings.watermark_x_space) / (defaultSettings.watermark_width + defaultSettings.watermark_x_space));
            defaultSettings.watermark_x_space = parseInt((page_width - defaultSettings.watermark_x - defaultSettings.watermark_width * defaultSettings.watermark_cols) / (defaultSettings.watermark_cols - 1));
        }
        //如果将水印行数设置为0，或水印行数设置过大，超过页面最大长度，则重新计算水印行数和水印y轴间隔
        if (defaultSettings.watermark_rows == 0 || (parseInt(defaultSettings.watermark_y + defaultSettings.watermark_height * defaultSettings.watermark_rows + defaultSettings.watermark_y_space * (defaultSettings.watermark_rows - 1)) > page_height)) {
            defaultSettings.watermark_rows = parseInt((defaultSettings.watermark_y_space + page_height - defaultSettings.watermark_y) / (defaultSettings.watermark_height + defaultSettings.watermark_y_space));
            defaultSettings.watermark_y_space = parseInt(((page_height - defaultSettings.watermark_y) - defaultSettings.watermark_height * defaultSettings.watermark_rows) / (defaultSettings.watermark_rows - 1));
        }

        var x;
        var y;
        for (var i = 0; i < defaultSettings.watermark_rows; i++) {
            y = defaultSettings.watermark_y + (defaultSettings.watermark_y_space + defaultSettings.watermark_height) * i;
            for (var j = 0; j < defaultSettings.watermark_cols; j++) {
                x = defaultSettings.watermark_x + (defaultSettings.watermark_width + defaultSettings.watermark_x_space) * j;

                var mask_div = document.createElement('div');
                var oText=document.createTextNode(defaultSettings.watermark_txt);
                mask_div.appendChild(oText);
                // 设置水印相关属性start
                mask_div.id = 'mask_div' + i + j;
                mask_div.onselectstart="return false";
                //设置水印div倾斜显示
                mask_div.style.filter = "progid:DXImageTransform.Microsoft.Matrix(sizingMethod='auto expand', M11=0.96593, M12=0.25882, M21=-0.25882, M22=0.96593) progid:DXImageTransform.Microsoft.Alpha(opacity=15)";
                mask_div.style.webkitTransform = "rotate(-" + defaultSettings.watermark_angle + "deg)";

                mask_div.style['-moz-transform'] = "rotate(-" + defaultSettings.watermark_angle + "deg)";
                mask_div.style['-ms-transform'] = "rotate(-" + defaultSettings.watermark_angle + "deg)";
                mask_div.style['-ot-transform'] = "rotate(-" + defaultSettings.watermark_angle + "deg)";
                mask_div.style.transform = "rotate(-" + defaultSettings.watermark_angle + "deg)";
                mask_div.style.visibility = "";
                mask_div.style.position = "absolute";
                //选不中

                mask_div.style.left = x + 'px';
                mask_div.style.top = y + 'px';
                mask_div.style.overflow = "hidden";
                mask_div.style.zIndex = "9999";
                //mask_div.style.border="solid #eee 1px";
                mask_div.style.opacity = defaultSettings.watermark_alpha;
                mask_div.style['-moz-opacity']=defaultSettings.watermark_alpha;
                mask_div.style['-khtml-opacity']= defaultSettings.watermark_alpha;
                // mask_div.style.filter = defaultSettings.watermark_progid;
                mask_div.style.fontSize = defaultSettings.watermark_fontsize;
                mask_div.style.fontFamily = defaultSettings.watermark_font;
                mask_div.style.color = defaultSettings.watermark_color;
                mask_div.style.textAlign = "center";
                mask_div.style.width = defaultSettings.watermark_width + 'px';
                mask_div.style.height = defaultSettings.watermark_height + 'px';
                mask_div.style.display = "block";
                //设置水印相关属性end
                //附加到文档碎片中
                watermarkDiv.appendChild(mask_div);
                watermarkDiv.style.cursor = "default";


                window.watermarkdivs.push(watermarkDiv); //控制页面大小变化时水印字体
            };
        };
        //一次性添加到document中
        document.body.appendChild(oTemp);
    };

    watermark.init = function(settings) {
        window.onload = function() {
            loadMark(settings);
        };
        window.onresize = function() {
            loadMark(settings);
        };
    };

    watermark.load = function(settings){
        loadMark(settings);
    };

})(window.watermark = {} );

页面使用

<script language="javascript" src="XX/XX/watermark.js"></script> //引入之前定义的watermark.js
<script type="text/javascript">
 $(function(){
            watermark.load(watermark_txt:"12222")   // watermark_txt 水印名称
        });
</script>