概述：

• 该方法照搬element-UI，文件地址 element-ui/src/utils/clickoutside，仅用于VUE2.X

使用方法（项目中存在 element-ui 和vue2.x 可以直接使用下面的代码）：

<template>
    <div v-clickoutside="handleClose"> 
     需要控制的元素
    </div>
</template>
<script>
import Clickoutside from "element-ui/src/utils/clickoutside";
export default {
  directives: { Clickoutside },
  methods: {
    handleClose() {
        console.log('元素内外分别点一下，触发的事件')
    },
  }
}
</script>

项目存在vue2.x 却没有element-ui 的情况下，需要手动操作一下以下代码：

clickoutside.js 代码

import Vue from 'vue';
import { on } from './dom.js';

const nodeList = [];
const ctx = '@@clickoutsideContext';

let startClick;
let seed = 0;

!Vue.prototype.$isServer && on(document, 'mousedown', e => (startClick = e));

!Vue.prototype.$isServer && on(document, 'mouseup', e => {
  nodeList.forEach(node => node[ctx].documentHandler(e, startClick));
});

function createDocumentHandler(el, binding, vnode) {
  return function(mouseup = {}, mousedown = {}) {
    if (!vnode ||
      !vnode.context ||
      !mouseup.target ||
      !mousedown.target ||
      el.contains(mouseup.target) ||
      el.contains(mousedown.target) ||
      el === mouseup.target ||
      (vnode.context.popperElm &&
      (vnode.context.popperElm.contains(mouseup.target) ||
      vnode.context.popperElm.contains(mousedown.target)))) return;

    if (binding.expression &&
      el[ctx].methodName &&
      vnode.context[el[ctx].methodName]) {
      vnode.context[el[ctx].methodName]();
    } else {
      el[ctx].bindingFn && el[ctx].bindingFn();
    }
  };
}

/**
 * v-clickoutside
 * @desc 点击元素外面才会触发的事件
 * @example
 * ```vue
 * <div v-element-clickoutside="handleClose">
 * ```
 */
export default {
  bind(el, binding, vnode) {
    nodeList.push(el);
    const id = seed++;
    el[ctx] = {
      id,
      documentHandler: createDocumentHandler(el, binding, vnode),
      methodName: binding.expression,
      bindingFn: binding.value
    };
  },
  update(el, binding, vnode) {
    el[ctx].documentHandler = createDocumentHandler(el, binding, vnode);
    el[ctx].methodName = binding.expression;
    el[ctx].bindingFn = binding.value;
  },
  unbind(el) {
    let len = nodeList.length;
    for (let i = 0; i < len; i++) {
      if (nodeList[i][ctx].id === el[ctx].id) {
        nodeList.splice(i, 1);
        break;
      }
    }
    delete el[ctx];
  }
};

dom.js 代码

/* istanbul ignore next */

import Vue from 'vue';

const isServer = Vue.prototype.$isServer;
const SPECIAL_CHARS_REGEXP = /([\:\-\_]+(.))/g;
const MOZ_HACK_REGEXP = /^moz([A-Z])/;
const ieVersion = isServer ? 0 : Number(document.documentMode);

/* istanbul ignore next */
const trim = function(string) {
  return (string || '').replace(/^[\s\uFEFF]+|[\s\uFEFF]+$/g, '');
};
/* istanbul ignore next */
const camelCase = function(name) {
  return name.replace(SPECIAL_CHARS_REGEXP, function(_, separator, letter, offset) {
    return offset ? letter.toUpperCase() : letter;
  }).replace(MOZ_HACK_REGEXP, 'Moz$1');
};

/* istanbul ignore next */
export const on = (function() {
  if (!isServer && document.addEventListener) {
    return function(element, event, handler) {
      if (element && event && handler) {
        element.addEventListener(event, handler, false);
      }
    };
  } else {
    return function(element, event, handler) {
      if (element && event && handler) {
        element.attachEvent('on' + event, handler);
      }
    };
  }
})();

/* istanbul ignore next */
export const off = (function() {
  if (!isServer && document.removeEventListener) {
    return function(element, event, handler) {
      if (element && event) {
        element.removeEventListener(event, handler, false);
      }
    };
  } else {
    return function(element, event, handler) {
      if (element && event) {
        element.detachEvent('on' + event, handler);
      }
    };
  }
})();

/* istanbul ignore next */
export const once = function(el, event, fn) {
  var listener = function() {
    if (fn) {
      fn.apply(this, arguments);
    }
    off(el, event, listener);
  };
  on(el, event, listener);
};

/* istanbul ignore next */
export function hasClass(el, cls) {
  if (!el || !cls) return false;
  if (cls.indexOf(' ') !== -1) throw new Error('className should not contain space.');
  if (el.classList) {
    return el.classList.contains(cls);
  } else {
    return (' ' + el.className + ' ').indexOf(' ' + cls + ' ') > -1;
  }
};

/* istanbul ignore next */
export function addClass(el, cls) {
  if (!el) return;
  var curClass = el.className;
  var classes = (cls || '').split(' ');

  for (var i = 0, j = classes.length; i < j; i++) {
    var clsName = classes[i];
    if (!clsName) continue;

    if (el.classList) {
      el.classList.add(clsName);
    } else if (!hasClass(el, clsName)) {
      curClass += ' ' + clsName;
    }
  }
  if (!el.classList) {
    el.setAttribute('class', curClass);
  }
};

/* istanbul ignore next */
export function removeClass(el, cls) {
  if (!el || !cls) return;
  var classes = cls.split(' ');
  var curClass = ' ' + el.className + ' ';

  for (var i = 0, j = classes.length; i < j; i++) {
    var clsName = classes[i];
    if (!clsName) continue;

    if (el.classList) {
      el.classList.remove(clsName);
    } else if (hasClass(el, clsName)) {
      curClass = curClass.replace(' ' + clsName + ' ', ' ');
    }
  }
  if (!el.classList) {
    el.setAttribute('class', trim(curClass));
  }
};

/* istanbul ignore next */
export const getStyle = ieVersion < 9 ? function(element, styleName) {
  if (isServer) return;
  if (!element || !styleName) return null;
  styleName = camelCase(styleName);
  if (styleName === 'float') {
    styleName = 'styleFloat';
  }
  try {
    switch (styleName) {
      case 'opacity':
        try {
          return element.filters.item('alpha').opacity / 100;
        } catch (e) {
          return 1.0;
        }
      default:
        return (element.style[styleName] || element.currentStyle ? element.currentStyle[styleName] : null);
    }
  } catch (e) {
    return element.style[styleName];
  }
} : function(element, styleName) {
  if (isServer) return;
  if (!element || !styleName) return null;
  styleName = camelCase(styleName);
  if (styleName === 'float') {
    styleName = 'cssFloat';
  }
  try {
    var computed = document.defaultView.getComputedStyle(element, '');
    return element.style[styleName] || computed ? computed[styleName] : null;
  } catch (e) {
    return element.style[styleName];
  }
};

/* istanbul ignore next */
export function setStyle(element, styleName, value) {
  if (!element || !styleName) return;

  if (typeof styleName === 'object') {
    for (var prop in styleName) {
      if (styleName.hasOwnProperty(prop)) {
        setStyle(element, prop, styleName[prop]);
      }
    }
  } else {
    styleName = camelCase(styleName);
    if (styleName === 'opacity' && ieVersion < 9) {
      element.style.filter = isNaN(value) ? '' : 'alpha(opacity=' + value * 100 + ')';
    } else {
      element.style[styleName] = value;
    }
  }
};

export const isScroll = (el, vertical) => {
  if (isServer) return;

  const determinedDirection = vertical !== null && vertical !== undefined;
  const overflow = determinedDirection
    ? vertical
      ? getStyle(el, 'overflow-y')
      : getStyle(el, 'overflow-x')
    : getStyle(el, 'overflow');

  return overflow.match(/(scroll|auto|overlay)/);
};

export const getScrollContainer = (el, vertical) => {
  if (isServer) return;

  let parent = el;
  while (parent) {
    if ([window, document, document.documentElement].includes(parent)) {
      return window;
    }
    if (isScroll(parent, vertical)) {
      return parent;
    }
    parent = parent.parentNode;
  }

  return parent;
};

export const isInContainer = (el, container) => {
  if (isServer || !el || !container) return false;

  const elRect = el.getBoundingClientRect();
  let containerRect;

  if ([window, document, document.documentElement, null, undefined].includes(container)) {
    containerRect = {
      top: 0,
      right: window.innerWidth,
      bottom: window.innerHeight,
      left: 0
    };
  } else {
    containerRect = container.getBoundingClientRect();
  }

  return elRect.top < containerRect.bottom &&
    elRect.bottom > containerRect.top &&
    elRect.right > containerRect.left &&
    elRect.left < containerRect.right;
};