Ruby

Call a JavaScript Function Returning a String

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

require 'chilkat'

success = false

# This is the JavaScript function we'll call:

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

sbScript = Chilkat::CkStringBuilder.new()
sbScript.Append("function greet(name) { return \"Hello, \" + name + \"!\"; }")

js = Chilkat::CkJs.new()

result = Chilkat::CkJsonObject.new()
result.put_EmitCompact(false)

# Call Eval to add the function to the context's global object
success = js.Eval(sbScript,result)
if (success == false)
    # Examine the result for an exception.
    print result.emit() + "\n";

    # Also examine the LastErrorText.
    print js.lastErrorText() + "\n";
    exit
end

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

funcCall = Chilkat::CkJsonObject.new()

# 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 == false)
    # Examine the result for an exception.
    print result.emit() + "\n";

    # Also examine the LastErrorText.
    print js.lastErrorText() + "\n";
    exit
end

print result.emit() + "\n";

# Output:
# {
#   "type": "string",
#   "value": "Hello, Michael!"
# }

retval = result.stringOf("value")
print retval + "\n";

# Output:
# Hello, Michael!