Description: Load data from the server and place the returned HTML into the matched element. Shareware Java applet and authoring tool that will run in any browser that supports Java 1.1 API allowing panoramas to be viewed on any platform. This specification provides an API for representing file objects in web applications, as well as programmatically selecting them and accessing their data. HTML5. A vocabulary and associated APIs for HTML and XHTMLW3. C Recommendation 2. October 2. 01. 46 Web application APIs. Scripting. 6. 1. 1 Introduction. Various mechanisms can cause author- provided executable code to run in the context of a. These mechanisms include, but are probably not limited to: 6. Processing model. Definitions. This specification describes three kinds of Java. Script global environments: the document environment, the. The. dedicated worker environment and the shared worker environment are both. Except where otherwise specified, a Java. Script global environment is a. A script has: A code entry- point. A code entry- point represents a block of executable code that the script exposes to other. Typically, the code corresponding to the code entry- point is. In Java. Script script blocks, this corresponds to the execution. Optionally, a muted errors flag. A flag which, if set, means that error information will not be provided for errors in this. A settings object. A script settings object, various settings that are shared with other scripts in. A script settings object specifies algorithms for obtaining the following: A script execution environment for each language supported by the user agent. The characteristics of the script execution environment depend on the language, and are not. In Java. Script, the script execution environment consists of the interpreter. Function objects resulting, and so forth. A global object. An object that provides the APIs that can be called by the code in scripts that use this. This is typically a Window object or a.
Worker. Global. Scope object. When a global object is an empty object, it. If the global object is a Window object, then, in. Java. Script, the This. Binding of the global execution context for this script must be the. Window object's Window. Proxy object, rather than the global object. The Java. Script specification requires that the this keyword in the global scope return the global object, but this is not. When a new script settings object is pushed onto. If this returns . They. return either . If the stack is. empty, or has no entries labeled as such, then there is no entry settings object. It is used. to obtain, amongst other things, the API base URL to resolve relative URLs used in scripts running in that. The incumbent settings object is the script settings object in the. If the stack is empty, then there is no incumbent settings object. It is used in some. The Web. IDL specification also uses these algorithms. Exploring the relationship between JavaScript and the modern HTML DOM. It is used to prevent reentrant invocation of. Mutation. Observer. For the purposes of Mutation. Observer objects, each unit of. Each unit of related similar- origin browsing contexts has a global script. A global script clean- up job cannot run. The File. API uses this to release blob: URLs. If the error is still not handled after this. Killing scripts. User agents may impose resource limitations on scripts, for example CPU quotas, memory limits. When a script exceeds a limit, the user. Quota. Exceeded. Error exception, abort the script without an. For example, the following script never terminates. A user agent could, after waiting for a. If there is no corresponding object, then the. Let location be an absolute URL that corresponds to the. The resource containing the script will typically be the file from which the. Document was parsed, e. Even for dynamically- generated scripts, user agents are strongly encouraged to attempt. For example, if an external script uses the. API to insert an inline. URL of the resource containing the script would. Naturally, implementing this can be somewhat. User agents are similarly encouraged to keep careful track of the original line. If script has muted errors, then set message to . Otherwise, the error is not handled. Runtime script errors in documents. Whenever an uncaught runtime script error occurs in one of the scripts associated with a. Document, the user agent must report the error for the relevant script, with the problematic position (line number and column. If the error is still not handled after this. The Error. Event interface. When the object is created, this attribute must be initialized to the. It represents the error message. The filename attribute must return the. When the object is created, this attribute must be initialized to the. It represents the absolute URL of the script in which the error. The lineno attribute must return the. When the object is created, this attribute must be initialized to. It represents the line number where the error occurred in the script. The colno attribute must return the value. When the object is created, this attribute must be initialized to zero. It. represents the column number where the error occurred in the script. The error attribute must return the value. When the object is created, this attribute must be initialized to null. This specification does not currently describe. An event loop always has at least one browsing context. If an. event loop's browsing contexts all go away. A browsing context always has an. An event loop has one or more task queues. A. task queue is an ordered list of tasks, which are. Events. Asynchronously dispatching an Event object at a particular. Event. Target object is often done by a dedicated task. Not all events are dispatched using the task queue, many are. Parsing. The HTML parser tokenizing one or more bytes, and then processing any. Callbacks. Calling a callback asynchronously is often done by a dedicated task. Using a resource. When an algorithm fetches a resource, if the fetching occurs. Reacting to DOM manipulation. Some elements have tasks that trigger in response to DOM manipulation, e. All the tasks from one particular task source and destined to a. The. user agent could then give keyboard and mouse events preference over other tasks three quarters of. A user agent may have one storage mutex. This mutex is used to control access to. At any one point, the storage mutex is either free, or. If a user agent does not implement a storage mutex, it is exempt from implementing. User agent implementors have to make a choice between two evils. On the one hand. not implementing the storage mutex means that there is a risk of data corruption: a site could. On the other hand, implementing the storage. Web Storage or. cookies, all other sites that try to use Web Storage or cookies are blocked until the first site. Whenever a script calls into a plugin, and. Processing model. An event loop must continually run through the following steps for as long as it. Run the oldest task on one of the event. Documents are not fully active. The user agent may pick any. If the storage mutex is now owned by the event loop, release it. If a task was run in the first step above, remove that task from its task. If this event loop is not a worker's event loop, run these. Perform a microtask checkpoint. Provide a stable state. If necessary, update the rendering or user interface of any Document or. Otherwise, if this event loop is running for a. Worker. Global. Scope, but there are no events in the event loop's task queues and the Worker. Global. Scope object's closing flag is true, then destroy the event. Return to the first step of the event loop. When a user agent is to perform a microtask checkpoint, if the performing a microtask checkpoint flag is false, then the user agent must run the following steps: Let the performing a microtask checkpoint flag be true. Perform a custom elements checkpoint. Wait until this task runs before continuing these. Replace the stack of script settings objects with the old stack of. Return to the caller. Some of the algorithms in this specification, for historical reasons, require the user agent to. This means running the following steps: If any asynchronously- running algorithms are awaiting a. While a user agent has a paused. User agents should remain responsive to user input. When a user agent is to obtain the storage mutex as part of running a task, it must run through the following steps: If the storage mutex is already owned by this task's event loop, then abort these steps. Otherwise, pause until the storage mutex can be taken by the. Take ownership of the storage mutex. Generic task sources. The following task sources are used by a number of mostly. The DOM manipulation task source. This task source is used for features that react to DOM manipulations, such as. The user interaction task source. This task source is used for features that react to user interaction, for. Asynchronous events sent in response to user input (e. These act as non- capture event. The Event. Handler callback function type describes how this is. Initially, event handlers must be set to null. Event handlers are exposed in one of two ways. The first way, common to all event handlers, is as an event handler IDL attribute. The second way is as an event handler content. Event handlers on HTML elements and some of the event handlers on. Window objects are exposed in this way. An event handler content attribute is a. The name of. the content attribute is the same as the name of the event. Event handler content attributes, when specified, must contain valid Java. Script. code which, when parsed, would match the Function. Body production after. Every event handler ends up registering the same. This only happens the first time the event. Since listeners are called in the order they were registered, the. Event. Listener() before. Event. Listener()after the. This example demonstrates the order in which event listeners are invoked. If the button in. Let. return value be the callback's return value. Let return value be the callback's return value. It is represented in Web IDL as follows: ? Event. Handler; In Java. Script, any Function object implements this interface. For example, the following document fragment: < body onload=. With beforeunload events. For historical reasons, the onerror handler has different. On. Error. Event. Handler; Similarly, the onbeforeunload handler has a. On. Before. Unload. Multiuser Drawing Pad Built with Pure Java. Script/HTML5/Canvas . The drawing pad updates in realtime when any connected user draws a line. Here's Union. Draw. Have a scribble! For maximum speed, the connection to Union Server is made over Web. Socket in browsers that support it. Where Web. Socket is not supported, Orbiter. Micro automatically falls back to Union platform's binary request model for responsive two- way communication over traditional HTTP. The drawing pad works in Firefox 3+, Chrome 1+, Safari 4+, i. Pad, i. Phone 3+, Android 2. Internet Explorer 8+, and Opera 9. Support for < canvas> in Internet Explorer 8 is provided by Google's Explorer. Canvas. Stripped of comments and line breaks, the code is about 3. Java. Script, and requires no server- side programming. The Code. Union. Draw is broken into two files: an HTML wrapper that provides the drawing canvas and basic user interface, and a Java. Script file that implements the application logic. Both files are shown below. Union. Draw requires access to a Union Server. In this example, we connect to the public test server tryunion. The multiuser aspects of the shared drawing program rely on three key Union platform features: rooms, client attributes, and room messages. Union. Draw's room is named . It gives users a place in which to share information, such as drawing commands and line styles. Upon joining the . For example, a user might receive an update such as: . Because users join . For example, a Union. Draw client never receives the position of the ball in the Union Pong room, which also runs on tryunion. Union. Draw's client attributes specify each user's current line thickness and color. The attributes are named, appropriately, . When a client changes its . To change an attribute, clients use the Message. Manager's send. UPC() command to send a SET. For example, the following code changes the attribute named . Unlike Orbiter and Reactor, Orbiter. Micro applications send raw UPC messages directly. The lower- level API keeps Orbiter. Micro's file size small, making Orbiter. Micro usable in bandwidth- limited environments, such as mobile devices. Union. Draw's room messages include the MOVE message and the PATH message. A client sends a MOVE room message when it wishes to inform other clients in the . A client sends a PATH room message when it wishes to inform other clients in the . The PATH room message includes the list of points in the new line. For example, the following code sends a . Each Union platform application defines its own attributes and messages, and uses its attributes to share data and its messages to send commands to the server and to other clients. Now here's the source code for Union. Draw. uniondraw. html. DOCTYPE HTML PUBLIC . Explorer. Canvas courtesy Google. Use during development.- ->. Use for production.- ->. See: http: //unionplatform. UPC = net. user. 1. UPC. // The ID of the room users will join in order to draw together. ID = . Each client sets a. MOVE means move the. PATH supplies a list of points to be. For a description of room. Snapshot. Listener()'s. This client receives the room. Assign that list to client. List. Split that string to get the attributes. When an attribute value changes, check to see whether it was either. But first. // bring the thickness into legal range if necessary (prevents thickness hacking). For. // details, see http: //unionplatform. Ignore the second event if the pen is already down. In. // other browsers, we invoke event. Default(). Attributes are automatically shared with other. Attribute. Update. Listener(). If the pen. Buffer a maximum.
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