Perl Requires Chilkat v11.4.0+

Call a JavaScript Function Returning an Integer

See more JavaScript Examples

Demonstrates how to call a JavaScript function that returns an integer. Chilkat2 Perl

use strict;
use warnings;
use Chilkat2;

# ----------------------------------------------------------------------------------
# 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.
my $sbScript = Chilkat2::StringBuilder->new;
my $success = $sbScript->LoadFile('js_call_function.js', 'utf-8');
if (!$success) {
    print $sbScript->LastErrorText, "\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.
my $js = Chilkat2::Js->new;

my $result = Chilkat2::JsonObject->new;
$result->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) {
    # Examine the result for an exception.
    print $result->Emit(), "\n";

    # Also examine the LastErrorText.
    print $js->LastErrorText, "\n";
    exit;
}

print $result->Emit(), "\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)

my $funcCall = Chilkat2::JsonObject->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->EmitCompact(0);
print $funcCall->Emit(), "\n";

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

    # Also examine the LastErrorText.
    print $js->LastErrorText, "\n";
    exit;
}

print $result->Emit(), "\n";

# Output:

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

my $retval = $result->IntOf('value');
print 'retval = ', $retval, "\n";

JavaScript

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