Xojo Plugin

Call a JavaScript Function Passing an Array Argument

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Demonstrates how to call a JavaScript function with an argument that is an array. Xojo Plugin

Dim success As Boolean
success = False

//  This is the JavaScript function we'll call:

//  function calculateTotal(numbers) {
//    console.log(numbers);
//    let total = 0;
//    
//    // Loop through every number in the array
//    for (const num of numbers) {
//      console.log(num);
//      total += num;
//    }
//    
//    return total;
//  }

Dim sbScript As New Chilkat.StringBuilder
success = sbScript.LoadFile("js_function_array_arg.js","utf-8")
If (success = False) Then
    System.DebugLog(sbScript.LastErrorText)
    Return
End If

Dim js As New Chilkat.Js

Dim result As New Chilkat.JsonObject
result.EmitCompact = False

//  Call Eval to add the function to the context's global object
success = js.Eval(sbScript,result)
If (success = False) Then
    //  Examine the result for an exception.
    System.DebugLog(result.Emit())

    //  Also examine the LastErrorText.
    System.DebugLog(js.LastErrorText)
    Return
End If

//  ------------------------------------------------------------------------------
//  Call the function calculateTotal(numbers)

Dim funcCall As New Chilkat.JsonObject
funcCall.EmitCompact = False

//  Create JSON specifying the function name and arguments
//  In this case, there is only 1 argument, and it is an array.

success = funcCall.UpdateString("name","calculateTotal")

//  Create the arguments array.
Dim argsArray As New Chilkat.JsonArray

//  The 1st argument in the arguments array is itself an array.
//  Passing -1 indicates to append to the array.
Dim arg As New Chilkat.JsonArray
success = argsArray.AddArrayAt2(-1,arg)

//  Fill in the values for the 1st argument.
success = arg.AddNumberAt(-1,"10.50")
success = arg.AddNumberAt(-1,"20.00")
success = arg.AddNumberAt(-1,"5.25")

//  Add the "args" array to the funcCall.
success = funcCall.AppendArrayCopy("args",argsArray)

System.DebugLog(funcCall.Emit())

//  The funcCall is as follows.  Notice that the 1st (and only) argument is an array.

//  {
//    "name": "calculateTotal",
//    "args": [
//      [
//        10.50,
//        20.00,
//        5.25
//      ]
//    ]
//  }

success = js.CallFunction(funcCall,result)
If (success = False) Then
    //  Examine the result for an exception.
    System.DebugLog(result.Emit())

    //  Also examine the LastErrorText.
    System.DebugLog(js.LastErrorText)
    Return
End If

System.DebugLog(result.Emit())

//  Result:
//  {
//    "type": "double",
//    "value": 35.75
//  }

//  The function also emitted text to the console.

Dim sbOut As New Chilkat.StringBuilder
js.ConsoleOutputSb sbOut
System.DebugLog(sbOut.GetAsString())

//  Output:
//  10.5,20,5.25
//  10.5
//  20
//  5.25

//  -----------------------------------------------------------
//  Note: If the array argument is simple, this is an alternative
//  and simpler way of creating the funcCall:

funcCall.Clear 
success = funcCall.UpdateString("name","calculateTotal")
success = funcCall.UpdateNumber("args[0][0]","10.50")
success = funcCall.UpdateNumber("args[0][1]","20.00")
success = funcCall.UpdateNumber("args[0][2]","5.25")
System.DebugLog(funcCall.Emit())

JavaScript

function calculateTotal(numbers) {
  console.log(numbers);
  let total = 0;
  
  // Loop through every number in the array
  for (const num of numbers) {
    console.log(num);
    total += num;
  }
  
  return total;
}