ios/android custom url schema support in your web page (viber example)

mobile-button.js

var $button = document.querySelector('.mobile-button'),
    $input = document.querySelector('.message-input');
$button.addEventListener('click', function (e) {
        e.preventDefault();
        send_msg($input.value);
});

function send_msg(text) {

    var app_url = "viber://forward?text=" + encodeURIComponent(text), /* custom schema url - app is launching, if it has been installed */
        url = "http://viber.com", /* if device not detected */
        ios_url = "https://itunes.apple.com/app/id382617920", /* open app in app store */
        android_url = "market://details?id=com.viber.voip"; /* open app in play market */

    if (navigator.userAgent.match(/iPhone|iPod|iPad/i)) {
        url = ios_url;
    } else if (navigator.userAgent.match(/android/i)) {
        url = android_url;
    }
    var iframe = document.getElementById("__mobilebuttontempiframe") || document.createElement('iframe');
    iframe.setAttribute('id', "__mobilebuttontempiframe");
    iframe.style.display = "none";
    iframe.style.border = "none";
    document.body.appendChild(iframe);
    iframe.src = app_url;
    setTimeout(function () {
        window.open(url, '_top');
    }, 300);
    return;
}