JS to determine if there is a client on the mobile side: open if it exists, download if it does not exist

Function Android () {        window.location.href = "Open App protocol";/*** Open App Protocol, Android colleague provides ***/        window.settimeout (function {           window.location.href = "Download the app's address";/***android mobile ***/        },2000);} function iOS () {        var IFR = document.createelement ("iframe");        IFR.SRC = "Open the app's protocol"; /*** Open the App protocol, have iOS colleague provided ***/        Ifr.style.display = "None";         Document.body.appendChild (IFR);        Window.settimeout (function () {          document.body.removeChild (IFR);           window.location.href = "Download the app's address"; /*** Download app address ***/        },2000)}var u = window.navigator.useragent;var isandroid = u.indexof (' Android ') >-1 | | U.indexof (' Linux ') >-1; Android Terminal or UC browser var Isios =!! U.match (/\ (i[^;] +;( U;)? Cpu.+mac OS x/); if (isandroid) {      android ();} if (Isios) {      iOS ();  }

　　

JS to determine if there is a client on the mobile side: open if it exists, download if it does not exist