Chrome browser Extensions Development Series Ten: Desktop Alert Notification__ppapi

Desktop Notification, also known as Web Notification, notifies users that an event has occurred in the form of a pop-up desktop dialog box outside the Web page. Web notification became the recommended standard of the WWW in 2015.9.10, the website https://www.w3.org/TR/notifications/. Each notification dialog box includes title, direction, language, and origin. The notification dialog box can also have body, tag, icon URL and icon image.

The notification must obtain the authorization of the user to be able to display, thereby avoiding user expectations of the notification interference. There are three authorizations for notifications, respectively, by the string "default" (user not explicitly authorized, with denied), "denied", "granted".

Because the display of notifications is related to the implementation of the browser and is related to the user's authorization, it is often appropriate to check the authorization of the browser and user before using desktop Alerts, as shown in the following example:

function Checknotification () {

if (! () Notification "in Window") {

Alert ("This browser does not support desktop notification");

}

Check whether notification permissions have alredy been granted

else if (notification.permission = = "Granted") {

If It ' s okay let ' s create a notification

New Notification ("granted!");

}

Otherwise, ask the user for permission

else if (notification.permission!== ' denied ') {

Notification.requestpermission (function (permission) {

If the user accepts, let ' s create a notification

if (Permission = = "Granted") {

New Notification ("Request granted!");

}

});

}

}

The Chrome chrome.notifications.* API can create desktop alerts based on templates and display notifications in the tray in the lower-right corner of the operating system.

To use notifications in the Chrome browser extensions, first declare the notifications permissions in the Manifest.json file as follows:

{

"Permissions": [

"Notifications"

],

}

Chrome.notifications.TemplateType is an enumeration type with the following enumeration values:

enumeration value	Comments
"Basic"	Default templates icon, title, message, Expandedmessage located on two button
"Image"	icon, title, message, Expandedmessage, image located on two button
"List"	icon, title, message, items located above two button
"Progress"	icon, title, message, progress located on two button

Chrome.notifications. Permissionlevel is an enumeration type with the following enumeration values:

enumeration value	Comments
"Granted"	Default, user authorization display notification
"Denied"	User not authorized to display notification

The properties of the Chrome.notifications.NotificationOptions object are as follows:

Property name	Type	Required/Optional	Comments
Type	Templatetype	Optional	Type of notification, Chrome.notifications.create () required to create notification
Title	String	Optional	The title of the notice, Chrome.notifications.create () required to create notification
Message	String	Optional	The subject content of the notification, Chrome.notifications.create () required to create notification
Contextmessage	String	Optional	Optional content of the notification
Buttons	Array of Object	Optional	The array has a maximum of 2 elements, representing 2 button respectively. Each button object has title and Iconurl two attributes (string types), where the Iconurl property is optional
Appiconmaskurl	String	Optional	The mask that applies the icon URL to the specification URL
Iconurl	String	Optional	The URL of the icon
ImageUrl	String	Optional	URL of a picture of a notification of type ' image '
Priority	Integer	Optional	Priority, valid range [ -2,2], default 0
Eventtime	Double	Optional	Notice of the time stamp, unit ms
Items	Array of Object	Optional	Each element in the array represents a notification. Each notification object has the title and message two attributes (String type)
Progress	Integer	Optional	Current progress, effective range [0,100]
Isclickable	Boolean	Optional	Whether the notification window responds to a click event

Common methods in the Chrome.notifications API:

· Create and display notifications

Chrome.notifications.create (

String Notificationid,

Notificationoptions options,

function (string Notificationid) {...}

)

The properties are described below:

Property name	Type	Required/optional	Comment
Notificationid	String	Optional	identifier for the notification. Generates a unique identifier automatically if it is not set or set to, If the value set is the same as the existing notification, replace the existing notification
Options	Notificationoptions	Must be selected