PowerShell

Call a JavaScript Function Returning an Integer

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Demonstrates how to call a JavaScript function that returns an integer. PowerShell

Add-Type -Path "C:\chilkat\ChilkatDotNet47-x64\ChilkatDotNet47.dll"

$success = $false

# ----------------------------------------------------------------------------------
# The Javascript function called in this example is shown at the bottom of this page.
# -----------------------------------------------------------------------------------

# In this example, we'll load the Javascript function definition from a file.
# It doesn't need to come from a file.  It could just as easily be loaded from a string.
$sbScript = New-Object Chilkat.StringBuilder
$success = $sbScript.LoadFile("js_call_function.js","utf-8")
if ($success -eq $false) {
    $($sbScript.LastErrorText)
    exit
}

# Note: Each instance of a Chilkat Js object automatically establishes
# its own internal runtime and context.  Applications do not need to explicitly create
# the JavaScript runtime or context.
$js = New-Object Chilkat.Js

$result = New-Object Chilkat.JsonObject
$result.EmitCompact = $false

# Call Eval to add the function (shown at the bottom of this page) to the context's global object
$success = $js.Eval($sbScript,$result)
if ($success -eq $false) {
    # Examine the result for an exception.
    $($result.Emit())

    # Also examine the LastErrorText.
    $($js.LastErrorText)
    exit
}

$($result.Emit())

# The expected output is "undefined":

# {
#   "type": "undefined",
#   "value": "undefined"
# }

#    When Eval processes a script containing only a function declaration,
#    it successfully performs the action (the function becomes defined).
#    However, since the script consists of a statement that produces no value,
#    the script's overall completion value is empty. In JavaScript, the
#    absence of a value is represented by `undefined`.
# 
#    Therefore, the Eval call returns `undefined`.

# ------------------------------------------------------------------------------
# Call the function calculateScore("Player1", 10, 20)

$funcCall = New-Object Chilkat.JsonObject

# Create JSON defining the function call:

# {
#   "name": "calculateScore",
#   "args": [ "Player1", 10, 20 ]
# }

$funcCall.UpdateString("name","calculateScore")
$funcCall.UpdateString("args[0]","Player1")
$funcCall.UpdateInt("args[1]",10)
$funcCall.UpdateInt("args[2]",20)

$funcCall.EmitCompact = $false
$($funcCall.Emit())

$success = $js.CallFunction($funcCall,$result)
if ($success -eq $false) {
    # Examine the result for an exception.
    $($result.Emit())

    # Also examine the LastErrorText.
    $($js.LastErrorText)
    exit
}

$($result.Emit())

# Output:

# {
#   "type": "int",
#   "value": 37
# }

$retval = $result.IntOf("value")
$("retval = " + $retval)