(Tcl) Call a JavaScript Function Returning an Integer

See more JavaScript Examples

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

Chilkat Tcl Extension Downloads Chilkat Tcl Extension Downloads

load ./chilkat.dll

set 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.
set sbScript [new_CkStringBuilder]

set success [CkStringBuilder_LoadFile $sbScript "js_call_function.js" "utf-8"]
if {$success == 0} then {
    puts [CkStringBuilder_lastErrorText $sbScript]
    delete_CkStringBuilder $sbScript
    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.
set js [new_CkJs]

set result [new_CkJsonObject]

CkJsonObject_put_EmitCompact $result 0

# Call Eval to add the function (shown at the bottom of this page) to the context's global object
set success [CkJs_Eval $js $sbScript $result]
if {$success == 0} then {
    # Examine the result for an exception.
    puts [CkJsonObject_emit $result]

    # Also examine the LastErrorText.
    puts [CkJs_lastErrorText $js]
    delete_CkStringBuilder $sbScript
    delete_CkJs $js
    delete_CkJsonObject $result
    exit
}

puts [CkJsonObject_emit $result]

# 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)

set funcCall [new_CkJsonObject]

# Create JSON defining the function call:

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

CkJsonObject_UpdateString $funcCall "name" "calculateScore"
CkJsonObject_UpdateString $funcCall "args[0]" "Player1"
CkJsonObject_UpdateInt $funcCall "args[1]" 10
CkJsonObject_UpdateInt $funcCall "args[2]" 20

CkJsonObject_put_EmitCompact $funcCall 0
puts [CkJsonObject_emit $funcCall]

set success [CkJs_CallFunction $js $funcCall $result]
if {$success == 0} then {
    # Examine the result for an exception.
    puts [CkJsonObject_emit $result]

    # Also examine the LastErrorText.
    puts [CkJs_lastErrorText $js]
    delete_CkStringBuilder $sbScript
    delete_CkJs $js
    delete_CkJsonObject $result
    delete_CkJsonObject $funcCall
    exit
}

puts [CkJsonObject_emit $result]

# Output:

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

set retval [CkJsonObject_IntOf $result "value"]
puts "retval = $retval"

delete_CkStringBuilder $sbScript
delete_CkJs $js
delete_CkJsonObject $result
delete_CkJsonObject $funcCall

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