6 Runtime System

This library implements the JavaScript runtime system. It be can required via:

(require (planet dherman/javascript:8:0/runtime))

6.1 Namespaces

(make-js-namespace) → namespace?

Creates a PLT namespace containing the standard JavaScript top-level bindings.

(reset-js-namespace! ns) → any

ns : namespace?

Resets the global object in JavaScript namespace ns.

6.2 Values

A JavaScript value is represented as one of:

• 'true: the JavaScript value true

• 'false: the JavaScript value false

• void?: the JavaScript undefined value

• null?: the JavaScript null value

• string?: a JavaScript primitive string value

• number?: a JavaScript primitive number value

• object?: a JavaScript object

• array?: a JavaScript primitive array object

6.3 Objects

JavaScript objects are represented with the following structure type:

(struct   object   (call construct proto class properties))

call : function?

construct : function?

proto : object?

class : string?

properties : (hash-of string? property?)

A JavaScript object.

A property is one of:

• property-value?

• attributed?

Plain value properties are assumed to have no attributes. An attributed value may have any combination of the attributes DONT-ENUM?, READ-ONLY?, and DONT-DELETE?.

(struct   attributed   (value attributes))

value : value?

attributes : bit-set?

A bit-set is an efficient representation of a set of booleans.

(bit-flag-set? x bit) → boolean?

x : bit-field?

bit : bit?

Checks for a bit in a bit set.

READ-ONLY? : bit?

A bit representing the ECMAScript ReadOnly attribute.

DONT-ENUM? : bit?

A bit representing the ECMAScript DontEnum attribute.

DONT-DELETE? : bit?

A bit representing the ECMAScript DontDelete attribute.

A property-value is one of:

• ref?

• value?

A ref is a special property with custom get, set, and delete behavior.

(ref? x) → boolean?

x : any

Determines whether x is a ref.

(set-ref! x v) → any

x : ref?

v : value?

Invoke x’s setter.

(delete-ref! x) → any

x : ref?

Invoke x’s deleter.

(deref x) → any

x : ref?

Invoke x’s getter.

JavaScript array values are represented specially for faster access of numeric properties:

(struct   (array object)   (vector))

vector : (evector-of property?)

(function? x) → boolean?

x : any

Determines whether a value is a callable object.

(has-property? x key) → boolean?

x : object?

key : string?

Checks for the presence of property key in x, searching the prototype chain if necessary.

(has-property/immediate x key) → boolean?

x : object?

key : string?

Checks for the presence of property key in x without searching the prototype chain.

(has-attribute? x bit) → boolean?

x : property?

bit : bit?

Checks for attribute bit in property x.

(object-get x key) → (optional/c value?)

x : object?

key : string?

Attempts to lookup property key in x.

(object-set! x key v) → any

x : object?

key : string?

v : value?

Sets property key in x.

(object-delete! x key) → any

x : object?

key : string?

Attempts to delete property key from x.

(object-keys-stream x) → (-> string?)

x : object?

Produces an enumeration stream consistent with JavaScript’s for..in semantics.

6.4 JavaScript Library

global-object : object?

The global object.

(install-standard-library! global) → any

global : object?

Installs the properties of the standard library in global.