@frontend_worker/search-selector/src/utils/dom.js

《远程搜索+单选》组件区别于element-ui或iview组件库的select远程搜索， ①将头部显示的值和下拉选项显示的值独立开来， ②避免远程加载时头部默认值显示异常， ③支持插槽自定义 ④将搜索框值放置于下拉弹框里面

import Vue from 'vue';
const isServer = Vue.prototype.$isServer;

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