This reference contains a list of standard ECMAScript objects, functions and properties supported by the plugin's JavaScript engine.

The Dynamic Script Engine Plugin scripting environment supports most JavaScript features up to ECMAScript level 7 (ECMA-262), as well as a handful of "Web API" features, or their close approximations.

This document lists all the supported objects and methods from the standards, with further details about items which do not fully match what is published on MDN, which is used as a reference.

Note: Some objects may only offer partial support for latest standards. In these cases, details of which properties/functions are supported per object type are shown below the main list and "details" links are provided.
Green links are to internal documentation details, blue links are external (MDN).

In some cases the standard objects are also extended (ArrayBuffer, Date, Math, Number, String, URL), as is the Global object, which is documented separately.

Nullish Coalescing (??) and Optional Chaining (?.) are also implemented.

Note that all Math functions are also available in the global scope, w/out the Math. qualifier.

Copyright: Portions of this text are originally from the Qt library's QJSEngine/QQmlEngine documentation, used under the GNU Free Documentation License.

Standard objects by category

Global (implementation details)

Fundamental objects

Numbers and dates

(Note lack of support for BigInt types.)

Text processing

Indexed Collections

Array (implementation details)
TypedArray (lacking support for at() method)
Int8Array
Uint8Array
Uint8ClampedArray
Int16Array
Uint16Array
Int32Array
Uint32Array
Float32Array
Float64Array

(Note lack of support for BigInt types.)

Keyed Collections

Structured data

Control Abstraction Objects

(Note that async functions/generators are not supported nor is the general async/await pattern. Use Promise instead.)

Reflection

Error objects

Web API

Global Functions:
- atob() - See notes at link.
- btoa() - See notes at link.
- setInterval() / clearInterval() (implementation details)
- setTimeout() / clearTimeout() (implementation details)
console (implementation details)
AbortController, AbortSignal (implementation details)
DOMException
fetch, Headers, Request, Response (implementation details)
URL & URLSearchParams (extended implementation)
WebSocket (implementation & extention details)
XMLHttpRequest (implementation details)

Details by object type

Any object type listed above but not here is presumed to have full compatibility as per MDN current documentation.

Global

Properties

NaN
Infinity
undefined
globalThis

Methods

eval(x)
parseInt(string, radix)
parseFloat(string)
isNaN(number)
isFinite(number)
decodeURI(encodedURI)
decodeURIComponent(encodedURIComponent)
encodeURI(uri)
encodeURIComponent(uriComponent)
escape(string)
unescape(string)
structuredClone(value [, options]) - via @ungap/structured-clone polyfill (supported options properties are extended). Since v1.3

See also: Global object extensions

Object

Supports all properties and methods described in MDN reference, except:

Object.fromEntries()
Object.hasOwn()

Array

Supports all properties and methods described in MDN reference, except:

Array.prototype.findLast()
Array.prototype.findLastIndex()
Array.prototype.flat()
Array.prototype.flatMap()
Array.prototype.group()
Array.prototype.groupToMap()

String

Supports all properties and methods described in MDN reference, except:

All methods marked deprecated (all are related to output formatting)
String.prototype.at()
String.prototype.matchAll()
String.prototype.replaceAll()

See also: String extensions

Promise

Promise.all()
Promise.race()
Promise.reject()
Promise.resolve()

Promise Prototype

Promise.prototype.catch()
Promise.prototype.finally()
Promise.prototype.then()

Web API

AbortController

signal
abort()
aborted (event)

AbortSignal

aborted
reason
throwIfAborted()
abort / onabort (event)

Note that in addition to the onabort property, there are other methods for connecting to the signal's abort event. signal.on("abort", callback), for example, which takes an optional, 3rd argument after the callback. If an object is passed here then the callback function will be invoked with that object as the this target. For example:

const xhr = XMLHttpRequest();
const ac = new AbortController();
// w/out the 2nd argument this will fail for async requests since the 'this' scope is lost.
ac.signal.on("abort", xhr.abort, xhr);

Alternately, the abort event can be safely connected directly to a method of any object. For example:

// note the switched argument positions vs the 'on("abort", ...)' signature.

ac.signal.abort.connect(xhr, xhr.abort);

See Event Handling for more details about connecting handlers to events.

Timers

setTimeout()/clearTimeout() and setInterval()/clearInterval(), are fully implemented as per standard (MDN reference), with some notes.
setTimeout() and setInterval() do accept optional arguments after the delay parameter, which are passed through to the function being invoked .
However only up to 5 parameters can be specified as positional arguments. If you need more, use an array. For example:
setTimeout(myFunctionWithArgs, 100, arg1, arg2, arg3); // ok

setTimeout(myFunctionWithArgs, 100, [ arg1, ... arg6 ]); // ok

setTimeout(myFunctionWithArgs, 100, arg1, ... arg6); // error

To pass a literal array as the first argument, wrap it in an array:
var arry = [1, 2, 3, 4];

setTimeout(myFunctionTakingAnArray, 100, arry); // will call -> myFunctionTakingAnArray(1, 2, 3, 4)

setTimeout(myFunctionTakingAnArray, 100, [ arry ]); // will call -> myFunctionTakingAnArray(arry)

setTimeout(myFunctionTakingAnArray, 100, arg1, arry); // will call -> myFunctionTakingAnArray(arg1, arry)
setTimeout() and setInterval() also accept an extended form of the first parameter, which is usually the function to invoke or string to evaluate. Instead, the first parameter can be an array with two values; the first value is the function to invoke and the second is the this scope object for calling the function with. This can avoid using an inline function in cases where this scope would typically be lost.
For example:
var xhr = XMLHttpRequest();

// ...

xhr.send();

setTimeout( [ xhr.abort, xhr ], 1000); // works (efficiently)

setTimeout(() => { xhr.abort() }, 1000); // works but creates unnecessary function and capture

setTimeout(xhr.abort, 1000); // possibly fails if the 'this' context for `xhr` is lost
See also clearAllTimers() and clearInstanceTimers()

console (Logging)

Function Properties

console.log() - same as console.debug()
console.debug()
console.info()
console.warn()
console.error()
console.assert()
console.time()
console.timeEnd()
console.trace()
console.count()
console.profile()
console.profileEnd()
console.dir(obj [,options]) - logs an object's properties, with recursion. Uses inspect() to get the output to print. Equivalent to console.debug(inspect(obj, options)). See inspect() for options details.

Extended functionality:

console.exception() - like console.error() but also prints stack trace.
print() - same as console.log()
printf(format, ...args) - writes formatted strings to the console log at "debug" level. Equivalent to console.log(sprintf(format, ...args)). See sprintf() for details.
console.logf(format, ...args), console.debugf(format, ...args), console.printf(format, ...args) - same as printf()
console.infof(format, ...args) - writes formatted string to console at "info" level. Equivalent to console.info(sprintf(format, ...args)).
console.warnf(format, ...args) - writes formatted string to console at "warning" level. Equivalent to console.warn(sprintf(format, ...args)).
console.errorf(format, ...args) - writes formatted string to console at "error" level. Equivalent to console.error(sprintf(format, ...args)).

XMLHttpRequest

The XMLHttpRequest object, which can be used to obtain data over a network using HTTP/s protocols.

The XMLHttpRequest API implements the same W3C standard as many popular web browsers with following exceptions:

XMLHttpRequest does not enforce the same origin policy (and in general, there is no "same origin" to enforce and any related security constraints are moot).
A redirect property has been added to control redirection response behavior. The options are similar to the standard Fetch API redirect option with some additions:
- follow: Automatically follow redirects. Unless otherwise stated the redirect mode is set to follow.
- error: Abort with an error if a redirect occurs.
- manual: Caller intends to process the response in another context.
- no-less-safe: Only allow http -> http, http -> https, and https -> https redirects (do not follow https -> http redirect); This is the default.
- same-origin: Only follow redirect if the original scheme, host, and port match.
A requestJSON property has been added, as a counterpart to the standard responseText and responseXML properties. This is equivalent to xhr.responseType = "json"; var obj = xhr.response;
A requestBuffer property has also been added. This is equivalent to xhr.responseType = "arraybuffer"; var arrayBuffer = xhr.response;
The following request properties can be accessed (set and read) individually. They can be set before the open() command, in which case open() can be called with no parameters. Or for example the URL can be set first, then open(method) called later.
- method - GET/POST/HEADERS/etc.
- url - URL of the request (can be a string or URL object).
- async - boolean value indicating whether to use asynchronous requests (default is true).
A headers property is added; This returns a two-dimensional array of header name/value pairs. For example:
[

[ 'Content-Type', 'application/json' ],

[ 'Accept', 'text/json, application/json' ]

]
- Before the send() method is called, this contains any headers explicitly added by the user with setRequestHeader().
- After send() and once the request has resolved, this will contain the response headers. These are the same headers obtained with getAllResponseHeaders() but in a structured format, possibly including duplicates as per HTTP spec (they are not merged as they would be with getAllResponseHeaders()).
  This will return an empty array if no headers have been received (yet, or in case of network error).

See also: Network APIs

Additionally, the responseXML XML DOM tree currently supported by DSEP4TP is a reduced subset of the DOM Level 3 Core API supported in a web browser. The following objects and properties are supported:

Node	Document	Element	Attr	CharacterData	Text
nodeName nodeValue nodeType parentNode childNodes firstChild lastChild previousSibling nextSibling attributes	xmlVersion xmlEncoding xmlStandalone documentElement	tagName	name value ownerElement	data length	isElementContentWhitespace wholeText