vue实现页面打印自动分页的两种方法

// 打印类属性、方法定义

const Print = function (dom, options) {
  if (!(this instanceof Print)) return new Print(dom, options);

  this.options = this.extend({
    'noPrint': '.no-print'
  }, options);

  if ((typeof dom) === "string") {
    this.dom = document.querySelector(dom);
  } else {
    this.isDOM(dom)
    this.dom = this.isDOM(dom) ? dom : dom.$el;
  }

  this.init();
};
Print.prototype = {
  init: function () {
    var content = this.getStyle() + this.getHtml();
    this.writeIframe(content);
  },
  extend: function (obj, obj2) {
    for (var k in obj2) {
      obj[k] = obj2[k];
    }
    return obj;
  },

  getStyle: function () {
    var str = "",
      styles = document.querySelectorAll('style,link');
    for (var i = 0; i < styles.length; i++) {
      str += styles[i].outerHTML;
    }
    str += "<style>" + (this.options.noPrint ? this.options.noPrint : '.no-print') + "{display:none;}</style>";
    str += "<style>html,body,div{height: auto!important;font-size:12px}</style>";

    return str;
  },

  getHtml: function () {
    var inputs = document.querySelectorAll('input');
    var textareas = document.querySelectorAll('textarea');
    var selects = document.querySelectorAll('select');

    for (var k = 0; k < inputs.length; k++) {
      if (inputs[k].type == "checkbox" || inputs[k].type == "radio") {
        if (inputs[k].checked == true) {
          inputs[k].setAttribute('checked', "checked")
        } else {
          inputs[k].removeAttribute('checked')
        }
      } else if (inputs[k].type == "text") {
        inputs[k].setAttribute('value', inputs[k].value)
      } else {
        inputs[k].setAttribute('value', inputs[k].value)
      }
    }

    for (var k2 = 0; k2 < textareas.length; k2++) {
      if (textareas[k2].type == 'textarea') {
        textareas[k2].innerHTML = textareas[k2].value
      }
    }

    for (var k3 = 0; k3 < selects.length; k3++) {
      if (selects[k3].type == 'select-one') {
        var child = selects[k3].children;
        for (var i in child) {
          if (child[i].tagName == 'OPTION') {
            if (child[i].selected == true) {
              child[i].setAttribute('selected', "selected")
            } else {
              child[i].removeAttribute('selected')
            }
          }
        }
      }
    }
    return this.dom.outerHTML;
    // 包裹要打印的元素
    // fix: https://github.com/xyl66/vuePlugs_printjs/issues/36
    // let outerHTML = this.wrapperRefDom(this.dom).outerHTML
    // return outerHTML;
  },
  // 向父级元素循环，包裹当前需要打印的元素
  // 防止根级别开头的 css 选择器不生效
  wrapperRefDom: function (refDom) {
    let prevDom = null
    let currDom = refDom
    // 判断当前元素是否在 body 中，不在文档中则直接返回该节点
    if (!this.isInBody(currDom)) return currDom

    while (currDom) {
      if (prevDom) {
        let element = currDom.cloneNode(false)
        element.appendChild(prevDom)
        prevDom = element
      } else {
        prevDom = currDom.cloneNode(true)
      }

      currDom = currDom.parentElement
    }

    return prevDom
  },

  writeIframe: function (content) {
    var w, doc, iframe = document.createElement('iframe'),
      f = document.body.appendChild(iframe);
    iframe.id = "myIframe";
    //iframe.style = "position:absolute;width:0;height:0;top:-10px;left:-10px;";
    iframe.setAttribute('style', 'position:absolute;width:0;height:0;top:-10px;left:-10px;');
    w = f.contentWindow || f.contentDocument;
    doc = f.contentDocument || f.contentWindow.document;
    doc.open();
    doc.write(content);
    doc.close();
    var _this = this
    iframe.onload = function(){
      _this.toPrint(w);
      setTimeout(function () {
        document.body.removeChild(iframe)
      }, 100)
    }
  },

  toPrint: function (frameWindow) {
    try {
      setTimeout(function () {
        frameWindow.focus();
        try {
          if (!frameWindow.document.execCommand('print', false, null)) {
            frameWindow.print();
          }
        } catch (e) {
          frameWindow.print();
        }
        frameWindow.close();
      }, 10);
    } catch (err) {
      console.log('err', err);
    }
  },
  // 检查一个元素是否是 body 元素的后代元素且非 body 元素本身
  isInBody: function (node) {
    return (node === document.body) ? false : document.body.contains(node);
  },
  isDOM: (typeof HTMLElement === 'object') ?
    function (obj) {
      return obj instanceof HTMLElement;
    } :
    function (obj) {
      return obj && typeof obj === 'object' && obj.nodeType === 1 && typeof obj.nodeName === 'string';
    }
};
const MyPlugin = {}
MyPlugin.install = function (Vue, options) {
  // 4. 添加实例方法
  Vue.prototype.$printPage = Print
}
export default MyPlugin

export default function printHtml(html) {
  let style = getStyle();
  let container = getContainer(html);
 
  document.body.appendChild(style);
  document.body.appendChild(container);
  getLoadPromise(container).then(() => {
    window.print();
    document.body.removeChild(style);
    document.body.removeChild(container);
  });
}
 
// 设置打印样式
function getStyle() {
let styleContent = `#print-container {
    display: none;
}
@media print {
    body > :not(.print-container) {
        display: none;
    }
    html,
    body {
      margin: 0 0.2cm;
      display: block !important;
      height:auto;
    }
    #print-container {
        display: block;
    }
    @page {
      margin: 0.25cm 0;
    }
}`;
  let style = document.createElement("style");
  style.innerHTML = styleContent;
  return style;
}
 
// 清空打印内容
function cleanPrint() {
  let div = document.getElementById('print-container')
  if (!!div) {
    document.querySelector('body').removeChild(div)
  }
}
 
// 新建DOM，将需要打印的内容填充到DOM
function getContainer(html) {
  cleanPrint()
  let container = document.createElement("div");
  container.setAttribute("id", "print-container");
  container.innerHTML = html;
  return container;
}
 
// 图片完全加载后再调用打印方法
function getLoadPromise(dom) {
  let imgs = dom.querySelectorAll("img");
  imgs = [].slice.call(imgs);
 
  if (imgs.length === 0) {
    return Promise.resolve();
  }
 
  let finishedCount = 0;
  return new Promise(resolve => {
    function check() {
      finishedCount++;
      if (finishedCount === imgs.length) {
        resolve();
      }
    }
    imgs.forEach(img => {
      img.addEventListener("load", check);
      img.addEventListener("error", check);
    })
  });
}