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Zone.js's support for standard apis

Zone.js patched most standard APIs such as DOM event listeners, XMLHttpRequest in Browser, EventEmitter and fs API in Node.js so they can be in zone.

In this document, all patched API are listed.

For non-standard APIs, please see NON-STANDARD-APIS.md

Patch Mechanisms

There are several patch mechanisms

  • wrap: makes callbacks run in zones, and makes applications able to receive onInvoke and onIntercept callbacks
  • Task: just like in the JavaScript VM, applications can receive onScheduleTask, onInvokeTask, onCancelTask and onHasTask callbacks
    1. MacroTask
    2. MicroTask
    3. EventTask

Some APIs which should be treated as Tasks, but are currently still patched in the wrap way. These will be patched as Tasks soon.

Browser

Web APIs

API Patch Mechanism Others
setTimeout/clearTimeout MacroTask app can get handlerId, interval, args, isPeriodic(false) through task.data
setImmediate/clearImmediate MacroTask same with setTimeout
setInterval/clearInterval MacroTask isPeriodic is true, so setInterval will not trigger onHasTask callback
requestAnimationFrame/cancelAnimationFrame MacroTask
mozRequestAnimationFrame/mozCancelAnimationFrame MacroTask
webkitRequestAnimationFrame/webkitCancelAnimationFrame MacroTask
alert wrap
prompt wrap
confirm wrap
Promise MicroTask
EventTarget EventTask see below Event Target for more details
HTMLElement on properties EventTask see below on properties for more details
XMLHttpRequest.send/abort MacroTask
XMLHttpRequest on properties EventTask
IDBIndex on properties EventTask
IDBRequest on properties EventTask
IDBOpenDBRequest on properties EventTask
IDBDatabaseRequest on properties EventTask
IDBTransaction on properties EventTask
IDBCursor on properties EventTask
WebSocket on properties EventTask
MutationObserver wrap
WebkitMutationObserver wrap
FileReader wrap
registerElement wrap

EventTarget

  • For browsers supporting EventTarget, Zone.js just patches EventTarget, so everything that inherits from EventTarget will also be patched.
  • For browsers that do not support EventTarget, Zone.js will patch the following APIs in the IDL that inherit from EventTarget
ApplicationCache EventSource FileReader InputMethodContext
MediaController MessagePort Node Performance
SVGElementInstance SharedWorker TextTrack TextTrackCue
TextTrackList WebKitNamedFlow Window Worker
WorkerGlobalScope XMLHttpRequest XMLHttpRequestEventTarget XMLHttpRequestUpload
IDBRequest IDBOpenDBRequest IDBDatabase IDBTransaction
IDBCursor DBIndex WebSocket

The following 'on' properties, such as onclick, onreadystatechange, are patched in Zone.js as EventTasks

copy cut paste abort
blur focus canplay canplaythrough
change click contextmenu dblclick
drag dragend dragenter dragleave
dragover dragstart drop durationchange
emptied ended input invalid
keydown keypress keyup load
loadeddata loadedmetadata loadstart message
mousedown mouseenter mouseleave mousemove
mouseout mouseover mouseup pause
play playing progress ratechange
reset scroll seeked seeking
select show stalled submit
suspend timeupdate volumechange waiting
mozfullscreenchange mozfullscreenerror mozpointerlockchange mozpointerlockerror
error webglcontextrestored webglcontextlost webglcontextcreationerror

NodeJS

API Patch Mechanism Others
setTimeout/clearTimeout MacroTask app can get handlerId, interval, args, isPeriodic(false) through task.data
setImmediate/clearImmediate MacroTask same with setTimeout
setInterval/clearInterval MacroTask isPeriodic is true, so setInterval will not trigger onHasTask callback
process.nextTick Microtask isPeriodic is true, so setInterval will not trigger onHasTask callback
Promise MicroTask
EventEmitter EventTask All APIs inherit EventEmitter are patched as EventTask
crypto MacroTask
fs MacroTask all async methods are patched

EventEmitter, addEventListener, prependEventListener and 'on' will be patched once as EventTasks, and removeEventListener and removeAllListeners will remove those EventTasks

Electron

Zone.js does not patch the Electron API, although in Electron both browser APIs and node APIs are patched, so if you want to include Zone.js in Electron, please use dist/zone-mix.js

ZoneAwareError

ZoneAwareError replaces global Error, and adds zone information to stack trace. ZoneAwareError also handles 'this' issue. This type of issue would happen when creating an error without new: this would be undefined in strict mode, and global in non-strict mode. It could cause some very difficult to detect issues.

  const error = Error(); 

ZoneAwareError makes sure that this is ZoneAwareError even without new.

ZoneAwarePromise

ZoneAwarePromise wraps the global Promise and makes it run in zones as a MicroTask. It also passes promise A+ tests.

BlackListEvents

Sometimes we don't want some event to be patched by zone.js, we can blacklist events by following settings.

    // disable on properties
    var targets = [window, Document, HTMLBodyElement, HTMLElement];
    __Zone_ignore_on_properties = [];
    targets.forEach(function (target) {
      __Zone_ignore_on_properties.push({
        target: target,
        ignoreProperties: ['scroll']
      });
    });

    // disable addEventListener
    global['__zone_symbol__BLACK_LISTED_EVENTS'] = ['scroll'];