当我从其他下拉列表中（特别是在iPad / iPhone中）选择值时，我想打开下拉列表。

Question

I want to open one drop down on the change event occurs on other drop down. The following code snippet is working fine for browser but it is not working on iPhone/iPad in Hybrid Application.

Your help will be appreciated.Please check Code snippet on jsfiddle

 function ViewModel(choices, choice) { this.choices = ko.observableArray(); this.choice = ko.observable(); this.changedropDown=function(data,event){ console.log("inside changedropDown"); this.bindDropDown(event); }; this.bindDropDown= function(event){ //event.stopPropagation(); console.log("insdie bindDropDown"); this.choices(choices); setTimeout(function() { showDropDown("xyz"); }, 500); }; }; var showDropDown = function (id) { console.log("inside showDropDown"); var dropdown = document.getElementById(id); var event = document.createEvent('MouseEvents'); event.initMouseEvent('mousedown', true, true, window); dropdown.dispatchEvent(event); }; var choices = [{ id: 1, name: "one" }, { id: 2, name: "two" }, { id: 3, name: "three" }]; ko.applyBindings(new ViewModel(choices)); 

 <script src="https://cdnjs.cloudflare.com/ajax/libs/knockout/3.2.0/knockout-min.js"></script> <select name="cars" data-bind="event:{change:function(data,event){changedropDown(data,event)}}"> <option value="volvo">Volvo</option> <option value="saab">Saab</option> <option value="fiat">Fiat</option> <option value="audi">Audi</option> </select> <select id="xyz" data-bind="options: choices, optionsText: 'name', value: choice"></select>