How to add back button event in Universal Windows

问题:

This is my main.js

(function () {
"use strict";

//No need of WinJS
var activation = Windows.ApplicationModel.Activation;
var roaming = Windows.Storage.ApplicationData.current.roamingSettings;

// For App Start Up
Windows.UI.WebUI.WebUIApplication.addEventListener("activated", function (args) {
    if (args.detail[0].kind === activation.ActivationKind.launch) {
        if (roaming.values["currentUri"]) {
            if (roaming.values["UserName"])
            {
                localStorage.setItem("UserName", roaming.values["UserName"]);
                window.location.href = roaming.values["currentUri"];
            }
        }
    }
});

// For App Suspension
Windows.UI.WebUI.WebUIApplication.addEventListener("suspending", function (args) {
    roaming.values["currentUri"] = window.location.href;
    roaming.values["UserName"] = localStorage.getItem("UserName");
});

// For Resuming App
Windows.UI.WebUI.WebUIApplication.addEventListener("resuming", function (args) {
    var roam = Windows.Storage.ApplicationData.current.roamingSettings;
    if (roam) {
        if (roam.values["currentUri"]) {
            localStorage.setItem("UserName", roam.values["UserName"]);
            window.location.href = roam.values["currentUri"];
        }
    }
}, false);
// not working backpressed event
Windows.UI.WebUI.WebUIApplication.addEventListener("backpressed", function (args) {
   // to do
}, false);})();

I need to add back key press event for windows phone without using winjs library? Can anyone suggest me?

I am using ms-appx-web context in my app. I dont want to use winjs library.

回答1:

I need to add back key press event for windows phone without using winjs library?

The backpressed event should be attached to Windows.Phone.UI.Input.HardwareButtons but not Windows.UI.WebUI.WebUIApplication.

If you refer to HardwareButtons.BackPressed and HardwareButtons, you will find the backpressed event is used like this:

var hardwareButtons = Windows.Phone.UI.Input.HardwareButtons;
function onBackPressed(eventArgs) { /* Your code */ }

// addEventListener syntax
hardwareButtons.addEventListener("backpressed", onBackPressed);
hardwareButtons.removeEventListener("backpressed", onBackPressed);

And since you are not making a Single Page Application. This event should be attached on every new page's JS codes.

Update: If you want to know your current device programmatically, you can use the following if-statement:

if (deviceInfo.operatingSystem.toLowerCase() == "windowsphone")
{
     //do your windows phone logic
} else if (deviceInfo.operatingSystem.toLowerCase() == "windows")
{
     //do your windows logic
}

回答2:

I used this-

var flag = Windows.Foundation.Metadata.ApiInformation.isTypePresent("Windows.Phone.UI.Input.HardwareButtons");

    if (flag) {
        var hardwareButtons = Windows.Phone.UI.Input.HardwareButtons;
        hardwareButtons.addEventListener("backpressed", onBackPressed);
    }

It worked for me well!