compatibility.md

VBScript Engine Compatibility

This document tracks the compatibility between this VBScript engine implementation and Microsoft's Internet Explorer VBScript engine.

Status Legend:

• ✔️ Implemented - Feature is fully or partially implemented
• ❌ Not Implemented - Feature is not yet implemented but may be in the future
• ⛔ Intentionally Not Implemented - Feature will not be implemented due to platform limitations

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Core Language Features

Data Types

Feature	Status	Notes
Empty	✔️
Null	✔️
Nothing	✔️
Boolean	✔️
Byte	✔️
Integer	✔️
Long	✔️
Single	✔️
Double	✔️
Currency	✔️
Date	✔️
String	✔️
Object	✔️
Variant	✔️
Error	✔️

Variables and Constants

Feature	Status	Notes
Dim	✔️
ReDim	✔️	With Preserve support
Const	✔️
Public	✔️
Private	✔️
Option Explicit	✔️

Operators

Feature	Status	Notes
Arithmetic (+, -, *, /)	✔️
Integer Division ()	✔️
Modulo (Mod)	✔️
Exponentiation (^)	✔️
Concatenation (&)	✔️
Comparison (=, <>, <, >, <=, >=)	✔️
Is	✔️
And	✔️
Or	✔️
Not	✔️
Xor	✔️
Eqv	✔️
Imp	✔️
Operator Precedence	✔️

Control Flow Statements

Feature	Status	Notes
If...Then...Else	✔️	Single-line and multi-line
ElseIf	✔️
For...Next	✔️	With Step support
For Each...Next	✔️
Do...Loop	✔️	While/Until variants
While...Wend	✔️
Select Case	✔️	With Case Else
Exit (Do/For/Sub/Function/Property)	✔️
With...End With	✔️
GoTo	✔️	With label support
On Error	✔️	Resume Next, GoTo 0
Resume	✔️	Partial implementation

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Procedures and Classes

Procedures

Feature	Status	Notes
Sub	✔️
Function	✔️
Call	✔️
ByVal	✔️
ByRef	✔️	Default behavior
Optional Parameters	✔️	With default values
ParamArray	✔️

Classes

Feature	Status	Notes
Class...End Class	✔️
New	✔️
Property Get	✔️
Property Let	✔️
Property Set	✔️
Me	✔️
Initialize Event	✔️	Class_Initialize
Terminate Event	✔️	Class_Terminate

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Built-in Functions

String Functions

Function	Status	Notes
Len	✔️
Left	✔️
Right	✔️
Mid	✔️
InStr	✔️
InStrRev	✔️
LCase	✔️
UCase	✔️
LTrim	✔️
RTrim	✔️
Trim	✔️
Replace	✔️
StrReverse	✔️
Space	✔️
String	✔️	Create repeated character string
Asc	✔️
AscW	✔️
Chr	✔️
ChrW	✔️
StrComp	✔️
Split	✔️
Join	✔️
Filter	✔️
Format	✔️	Custom format strings
LSet	✔️
RSet	✔️

Mathematical Functions

Function	Status	Notes
Abs	✔️
Sgn	✔️
Sqr	✔️
Int	✔️
Fix	✔️
Round	✔️
Atn	✔️
Cos	✔️
Sin	✔️
Tan	✔️
Exp	✔️
Log	✔️	Natural logarithm
Rnd	✔️
Randomize	✔️
Hex	✔️
Oct	✔️

Date and Time Functions

Function	Status	Notes
Now	✔️
Date	✔️
Time	✔️
Year	✔️
Month	✔️
Day	✔️
Weekday	✔️
Hour	✔️
Minute	✔️
Second	✔️
DateAdd	✔️
DateDiff	✔️
DatePart	✔️
DateSerial	✔️
TimeSerial	✔️
DateValue	✔️
TimeValue	✔️
MonthName	✔️
WeekdayName	✔️
Timer	✔️

Conversion Functions

Function	Status	Notes
CBool	✔️
CByte	✔️
CCur	✔️
CDate	✔️
CDbl	✔️
CInt	✔️
CLng	✔️
CSng	✔️
CStr	✔️
CVar	✔️
CVErr	✔️
Val	✔️
Str	✔️
FormatNumber	✔️	Uses Intl API with locale support
FormatCurrency	✔️	Auto-detects currency from locale
FormatPercent	✔️	Uses Intl API with locale support
FormatDateTime	✔️	Uses Intl API with locale support

Inspection Functions

Function	Status	Notes
IsArray	✔️
IsDate	✔️
IsEmpty	✔️
IsNull	✔️
IsNumeric	✔️
IsObject	✔️
VarType	✔️
TypeName	✔️

Array Functions

Function	Status	Notes
Array	✔️
LBound	✔️
UBound	✔️
Erase	✔️	Full implementation for fixed-size arrays
Filter	✔️

Other Functions

Function	Status	Notes
Eval	✔️
Execute	✔️	Dynamic code execution in current scope
ExecuteGlobal	✔️	Dynamic code execution in global scope
MsgBox	✔️	Browser simulation using alert/confirm
InputBox	✔️	Browser simulation using prompt
GetRef	✔️
GetLocale	✔️	Uses Intl API to detect browser locale
SetLocale	✔️	Sets locale, returns LCID
CreateObject	⛔	COM objects unavailable in browser
GetObject	⛔	COM objects unavailable in browser
LoadPicture	✔️	Returns stub IPictureDisp object
RGB	✔️	Returns RGB color value
QBColor	✔️	Returns legacy color value
ScriptEngine	✔️	Returns "VBScript"
ScriptEngineMajorVersion	✔️	Returns 10
ScriptEngineMinorVersion	✔️	Returns 8
ScriptEngineBuildVersion	✔️	Returns 16384

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Objects

Err Object

Property/Method	Status	Notes
Number	✔️
Description	✔️
Source	✔️
Clear	✔️
Raise	✔️
HelpContext	⛔	Windows Help system
HelpFile	⛔	Windows Help system

RegExp Object

Feature	Status	Notes
RegExp Object	✔️
Pattern	✔️
Global	✔️
IgnoreCase	✔️
Multiline	✔️
Execute Method	✔️
Test Method	✔️
Replace Method	✔️
Match Object	✔️	FirstIndex, Length, Value
Matches Collection	✔️	Count, Item
SubMatches Collection	✔️

Class Object

Feature	Status	Notes
Class definition	✔️
Public members	✔️
Private members	✔️
Property procedures	✔️
Methods	✔️

VBArray Object (JavaScript-side)

VBArray is a JavaScript-side object for accessing VBScript arrays from JavaScript. It provides backward compatibility with early Internet Explorer, which required wrapping VBScript arrays before accessing them from JavaScript.

Feature	Status	Notes
VBArray constructor	✔️	Wraps internal VbArray for JS access
dimensions()	✔️	Returns number of dimensions
lbound()	✔️	Returns lower bound of a dimension
ubound()	✔️	Returns upper bound of a dimension
getItem()	✔️	Gets value at specified indices
toArray()	✔️	Converts to JavaScript array

Configuration: The injectVBArrayToGlobalThis option (default: true) controls whether VBArray is available as globalThis.VBArray. When enabled, legacy code using new VBArray(vbArray) will work. Modern code can access VBScript arrays directly without wrapping.

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Statements

Statement	Status	Notes
Call	✔️
Class	✔️
Const	✔️
Dim	✔️
Do...Loop	✔️
Erase	✔️
Execute	✔️
ExecuteGlobal	✔️
Exit	✔️
For...Next	✔️
For Each...Next	✔️
Function	✔️
GoTo	✔️
If...Then...Else	✔️
On Error	✔️
Option Explicit	✔️
Private	✔️
Property Get/Let/Set	✔️
Public	✔️
Randomize	✔️
ReDim	✔️
Rem	✔️
Select Case	✔️
Set	✔️
Sub	✔️
While...Wend	✔️
With	✔️

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Constants

String Constants

Constant	Status	Notes
vbCr	✔️
vbCrLf	✔️
vbFormFeed	✔️
vbLf	✔️
vbNewLine	✔️
vbNullChar	✔️
vbNullString	✔️
vbTab	✔️
vbVerticalTab	✔️

VarType Constants

Constant	Status	Notes
vbEmpty	✔️
vbNull	✔️
vbInteger	✔️
vbLong	✔️
vbSingle	✔️
vbDouble	✔️
vbCurrency	✔️
vbDate	✔️
vbString	✔️
vbObject	✔️
vbError	✔️
vbBoolean	✔️
vbVariant	✔️
vbByte	✔️
vbArray	✔️

MsgBox Constants

Constant	Status	Notes
vbOKOnly	✔️
vbOKCancel	✔️
vbAbortRetryIgnore	✔️
vbYesNoCancel	✔️
vbYesNo	✔️
vbRetryCancel	✔️
vbCritical	✔️
vbQuestion	✔️
vbExclamation	✔️
vbInformation	✔️
vbDefaultButton1/2/3	✔️
vbOK	✔️
vbCancel	✔️
vbAbort	✔️
vbRetry	✔️
vbIgnore	✔️
vbYes	✔️
vbNo	✔️

Date Constants

Constant	Status	Notes
vbSunday - vbSaturday	✔️
vbUseSystemDayOfWeek	✔️
vbFirstJan1	✔️
vbFirstFourDays	✔️
vbFirstFullWeek	✔️
vbGeneralDate	✔️
vbLongDate	✔️
vbShortDate	✔️
vbLongTime	✔️
vbShortTime	✔️

Comparison Constants

Constant	Status	Notes
vbBinaryCompare	✔️
vbTextCompare	✔️
vbDatabaseCompare	✔️	Falls back to locale-aware comparison

Other Constants

Constant	Status	Notes
vbObjectError	✔️

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COM Objects

All COM objects features are intentionally not implemented due to browser security restrictions.

These functions rely on the JavaScript environment's native ActiveXObject support. In Internet Explorer, this allows creating COM objects including FileSystemObject, Word.Application, Excel.Application, etc. However, modern JavaScript environments (Chrome, Firefox, Edge, Node.js) do not support ActiveXObject. The author of this project may create a separate project in the future to implement polyfills for common COM objects (such as FileSystemObject, WScript.Shell, etc.) in modern JavaScript environments. This is beyond the scope of this VBScript engine project.

Feature	Status	Notes
FileSystemObject	⛔	Browser security
Drive Object	⛔	Browser security
Folder Object	⛔	Browser security
File Object	⛔	Browser security
TextStream	⛔	Browser security
Dictionary Object	⛔	Browser security

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Events

Event	Status	Notes
Initialize	✔️	Class_Initialize
Terminate	✔️	Class_Terminate

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Keywords

Keyword	Status	Notes
Empty	✔️
False	✔️
Nothing	✔️
Null	✔️
True	✔️
Me	✔️