PowerShell

Call a JavaScript Function Returning a String

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Demonstrates how to call a JavaScript function that returns a string. PowerShell

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

$success = $false

# This is the JavaScript function we'll call:

# function greet(name) {
#     return "Hello, " + name + "!";
# }

$sbScript = New-Object Chilkat.StringBuilder
$sbScript.Append("function greet(name) { return `"Hello, `" + name + `"!`"; }")

$js = New-Object Chilkat.Js

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

# Call Eval to add the function 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
}

# ------------------------------------------------------------------------------
# Call the function greet("Michael")

$funcCall = New-Object Chilkat.JsonObject

# Create JSON specifying the function name and arguments

# {
#   "name": "greet",
#   "args": [ "Michael" ]
# }

$funcCall.UpdateString("name","greet")
$funcCall.UpdateString("args[0]","Michael")

$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": "string",
#   "value": "Hello, Michael!"
# }

$retval = $result.StringOf("value")
$($retval)

# Output:
# Hello, Michael!