HTML页面添加自定义水印（watermark）

在需要引入HTML页面添加方法

 $(document).ready(function () {
        // 开启水印
        watermark.set('雨天路滑 小心驾驶');

        // 关闭水印
       // watermark.del();

    });

页面添加水印效果

/**

 * 页面添加水印效果
 * @method set 设置水印
 * @method del 删除水印
 */
const watermark = {
    // 设置水印
    set: (str) => {
        let id = setWatermark(str);
        if (document.getElementById(id) === null)
            id = setWatermark(str);
    },

    // 删除水印
    del: () => {
        let id = '1.99654.234';
            if (document.getElementById(id) !== null)
                document.body.removeChild(document.getElementById(id));
    }

};

const setWatermark = (str) => {
    const id = '1.99654.234';
    if (document.getElementById(id) !== null) document.body.removeChild(document.getElementById(id));
    const can = document.createElement('canvas');
    can.width = 200;
    can.height = 130;
    const cans = can.getContext('2d');
    cans.rotate((-20 * Math.PI) / 180);
    cans.font = '12px Vedana';
    cans.fillStyle = 'rgba(200, 200, 200, 0.30)';
    cans.textBaseline = 'Middle';
    cans.fillText(str, can.width / 10, can.height / 2);
    const div = document.createElement('div');
    div.id = id;
    div.style.pointerEvents = 'none';
    div.style.top = '15px';
    div.style.left = '0px';
    div.style.position = 'fixed';
    div.style.zIndex = '10000000';
    div.style.width = `${document.documentElement.clientWidth}px`;
    div.style.height = `${document.documentElement.clientHeight}px`;
    div.style.background = `url(${can.toDataURL('image/png')}) left top repeat`;
    document.body.appendChild(div);
    return id;
};

效果图