B4J Library [Web] [B4X] MiniJS

Version 0.60
GitHub: https://github.com/pyhoon/MiniJs-B4X

MiniJS-B4X is a B4X library that allows you to generate JavaScript code programmatically from your B4X applications. It provides a fluent API for building JavaScript code structures including functions, loops, conditionals, variables, objects, arrays, and more.

Features​

• Fluent API - Chainable methods for building JavaScript code
• Code Generation - Generate functions, loops, conditionals, variables, objects, arrays
• Indentation Management - Automatic indentation handling
• Comments Support - Single-line, multi-line, and inline comments
• Control Structures - Functions, if/else, for loops, try/catch
• Variables - const/let declarations with optional initialization
• Objects & Arrays - Object literals and array literals
• Function Calls - Method calls and function calls with arguments
• Event Listeners - Event listener generation
• Custom Events - CustomEvent dispatching
• Template Literals - Template string support

Installation​

1. Copy MiniJS.b4xlib from the release folder to your B4X additional libraries folder
2. In B4X IDE Libraries Manager tab, check the MiniJS library

Example:

Sub Process_Globals
    Private jsGen As MiniJS
End Sub

Sub AppStart (Args() As String)
    jsGen.Initialize
  
    ' Generate a sample function
    GenerateSampleFunction
  
    ' Get generated code with script tags
    Dim jsCode As String = jsGen.Generate
  
    ' Or without script tags
    Dim jsCodeRaw As String = jsGen.Generate2
  
    Log(jsCode)
End Sub

Private Sub GenerateSampleFunction
    jsGen.AddMultiLineComment("Sample generated JavaScript function" & CRLF & "Generated by B4J")
  
    ' Start function: function calculateTotal(items, taxRate) {
    jsGen.StartFunction("calculateTotal", Array As String("items", "taxRate"))
  
    ' let subtotal = 0;
    jsGen.DeclareVariable("subtotal", "0", False)
  
    ' for (let i = 0; i < items.length; i++) {
    jsGen.StartForLoop("let i = 0", "i < items.length", "i++")
  
    '     subtotal += items[i].price;
    jsGen.AddLine("subtotal += items[i].price;")
  
    ' }
    jsGen.EndForLoop
  
    ' if (taxRate > 0) {
    jsGen.StartIf("taxRate > 0")
  
    '     const tax = subtotal * taxRate;
    jsGen.DeclareVariable("tax", "subtotal * taxRate", True)
  
    '     return subtotal + tax;
    jsGen.AddLine("return subtotal + tax;")
  
    ' } else {
    jsGen.AddElse
  
    '     return subtotal;
    jsGen.AddLine("return subtotal;")
  
    ' }
    jsGen.EndIf
  
    ' }
    jsGen.EndFunction
End Sub

Output:

    /*
     * Sample generated JavaScript function
     * Generated by B4J
     */
    function calculateTotal (items, taxRate) {
        let subtotal = 0;
        for (let i = 0; i < items.length; i++) {
            subtotal += items[i].price;
        }
        if (taxRate > 0) {
            const tax = subtotal * taxRate;
            return subtotal + tax;
        } else {
            return subtotal;
        }
    }

API Reference​

Initialization​

Method	Description
Initialize	Initialize the generator

Code Generation​

Method	Description
Generate As String	Generate complete JS code wrapped in script tags
Generate2 As String	Generate complete JS code without script tags

Indentation​

Method	Description
IncreaseIndent	Increase indentation level
DecreaseIndent	Decrease indentation level

Comments​

Method	Description
AddComment(comment As String)	Add single-line comment
AppendComment(comment As String)	Append comment to current line
AddMultiLineComment(comment As String)	Add multi-line comment block
AddNewLine	Add blank line

Functions​

Method	Description
StartFunction(name As String, parameters() As String)	Start function declaration
EndFunction	End function declaration

Control Flow​

Method	Description
StartIf(condition As String)	Start if statement
ElseIf(condition As String)	Add else if clause
AddElse	Add else clause
EndIf	End if statement
StartForLoop(initializer, condition, increment)	Start for loop
EndForLoop	End for loop
StartTry	Start try block
AddCatch(event As String)	Add catch block
EndTry	End try/catch block

Variables​

Method	Description
DeclareVariable(name, value, isConst)	Declare const/let variable

Objects & Arrays​

Method	Description
CreateObject(name, properties As Map)	Create object literal
CreateArray(name, items As List)	Create array literal

Function & Method Calls​

Method	Description
AddFunctionCall(functionName, args())	Call function
AddMethodCall(objectName, methodName, args())	Call method on object

Events​

Method	Description
AddEventListener(functionName, eventName)	Add event listener
AddCustomEventDispatch(eventName, detailData As Map)	Dispatch custom event

Console​

Method	Description
ConsoleLog(message)	Generate console.log()
ConsoleError(message, event)	Generate console.error()

Conditionals​

Method	Description
AddConditionalCall(condition, call)	Inline conditional call
AddTernary(condition, trueExpr, falseExpr)	Ternary operator

 

[aeric]

Version 0.20

What's New​

1. Added AddCustomEventDispatch sub

 

[aeric]

Version 0.30

What's New​

1. Added Generate2 sub --> No script tags
2. Added IncreaseIndent and DecreaseIndent sub
3. Renamed Else sub to AddElse

 

[aeric]

Version 0.40

What's New​

1. Added ConsoleError sub
2. Added ConsoleLog sub
3. Added StartTry sub
4. Added AddCatch sub
5. Added EndTry sub
6. Removed StartCondition sub
7. Removed EndCondition sub
8. Changed AddMethodCall sub not to return value

 

[aeric]

Version 0.50

What's New​

1. Added AddTernary sub
2. Added AddEventListener sub
3. Added more comments

 

[aeric]

Version 0.60

What's New​

1. Added AddNewLine sub
2. Added AppendComment sub
3. Updated AddLine sub
4. Renamed variables

 

[aeric]

Updated library description in post #1.

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