(Perl) Call a JavaScript Function Returning an Integer

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Note: This example requires Chilkat v11.4.0 or greater.

Chilkat Perl Downloads Perl Module for Windows, MacOS, Linux, Alpine Linux

use chilkat();

$success = 0;

# ----------------------------------------------------------------------------------
# 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 = chilkat::CkStringBuilder->new();
$success = $sbScript->LoadFile("js_call_function.js","utf-8");
if ($success == 0) {
    print $sbScript->lastErrorText() . "\r\n";
    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 = chilkat::CkJs->new();

$result = chilkat::CkJsonObject->new();
$result->put_EmitCompact(0);

# 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 == 0) {
    # Examine the result for an exception.
    print $result->emit() . "\r\n";

    # Also examine the LastErrorText.
    print $js->lastErrorText() . "\r\n";
    exit;
}

print $result->emit() . "\r\n";

# 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 = chilkat::CkJsonObject->new();

# 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->put_EmitCompact(0);
print $funcCall->emit() . "\r\n";

$success = $js->CallFunction($funcCall,$result);
if ($success == 0) {
    # Examine the result for an exception.
    print $result->emit() . "\r\n";

    # Also examine the LastErrorText.
    print $js->lastErrorText() . "\r\n";
    exit;
}

print $result->emit() . "\r\n";

# Output:

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

$retval = $result->IntOf("value");
print "retval = " . $retval . "\r\n";

function calculateScore(name, pointsA, pointsB) {
    // Return length of name + both scores
    return name.length + pointsA + pointsB;
    }