简单实现vue项目给页面添加水印

首先编写生成水印的js代码，如下：

let watermark = {};

let setWatermark = (text, sourceBody) => {
  let id =
    Math.random() * 10000 +
    "-" +
    Math.random() * 10000 +
    "/" +
    Math.random() * 10000;

  if (document.getElementById(id) !== null) {
    document.body.removeChild(document.getElementById(id));
  }

  let can = document.createElement("canvas");
  can.width = 330; //设置水印之间的左右间距
  can.height = 220; //设置水印之间的上下间距

  let cans = can.getContext("2d");
  cans.rotate((-20 * Math.PI) / 150);
  cans.font = "12px Vedana";
  cans.fillStyle = "rgba(0, 0, 0, .2)";
  cans.textAlign = "left";
  cans.textBaseline = "Middle";
  cans.fillText(text, can.width / 20, can.height);

  let water_div = document.createElement("div");
  water_div.id = id;
  water_div.className = "watermarkClass";
  water_div.style.pointerEvents = "none";
  water_div.style.background =
    "url(" + can.toDataURL("image/png") + ") left top repeat";
  if (sourceBody) {
    water_div.style.width = "100%";
    water_div.style.height = "100%";
    sourceBody.appendChild(water_div);
  } else {
    water_div.style.top = "3px";
    water_div.style.left = "0px";
    water_div.style.position = "fixed";
    water_div.style.zIndex = "100000";
    water_div.style.width = document.documentElement.clientWidth + "px";
    water_div.style.height = document.documentElement.clientHeight + "px";
    document.body.appendChild(water_div);
  }

  return id;
};

/**
 *  该方法只允许调用一次
 *  @param:
 *  @text == 水印内容
 *  @sourceBody == 水印添加的位置，不传就是body
 * */
watermark.set = (text, sourceBody) => {
  const domArr = Array.from(document.getElementsByClassName("watermarkClass"));
  for (let i = 0; i < domArr.length; i++) {
    const element = domArr[i];
    // element.parentNode.removeChild(element);
    element.remove();
  }
  if (text == "") {
    return;
  }
  setWatermark(text, sourceBody);
  // let id = setWatermark(text, sourceBody);
  // setInterval(() => {
  //   if (document.getElementById(id) === null) {
  //     id = setWatermark(text, sourceBody);
  //   }
  // }, 2000);
  // window.onresize = () => {
  //   setWatermark(text, sourceBody);
  // };
};

export default watermark;

将此js文件放到项目某个目录，我这边是src/utils目录里

然后在main.js中引入此工具文件

// 引入水印文件地址
import watermark from './utils/watermark.js'
Vue.prototype.$watermark = watermark

在需要水印的页面中，在页面的created，mounted生命节点调用此接口生成想要的水印

mounted(){
     this.$watermark.set(this.userInfo.name+"/"+this.userInfo.code) //设置水印
},
created(){
     this.$watermark.set('') //清除水印
}