Delphi DLL Requires Chilkat v11.4.0+

Call a JavaScript Function Returning a String

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Demonstrates how to call a JavaScript function that returns a string. Delphi DLL

var
success: Boolean;
sbScript: HCkStringBuilder;
js: HCkJs;
result: HCkJsonObject;
funcCall: HCkJsonObject;
retval: PWideChar;

begin
success := False;

//  This is the JavaScript function we'll call:

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

sbScript := CkStringBuilder_Create();
CkStringBuilder_Append(sbScript,'function greet(name) { return "Hello, " + name + "!"; }');

js := CkJs_Create();

result := CkJsonObject_Create();
CkJsonObject_putEmitCompact(result,False);

//  Call Eval to add the function to the context's global object
success := CkJs_Eval(js,sbScript,result);
if (success = False) then
  begin
    //  Examine the result for an exception.
    Memo1.Lines.Add(CkJsonObject__emit(result));

    //  Also examine the LastErrorText.
    Memo1.Lines.Add(CkJs__lastErrorText(js));
    Exit;
  end;

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

funcCall := CkJsonObject_Create();

//  Create JSON specifying the function name and arguments

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

CkJsonObject_UpdateString(funcCall,'name','greet');
CkJsonObject_UpdateString(funcCall,'args[0]','Michael');

success := CkJs_CallFunction(js,funcCall,result);
if (success = False) then
  begin
    //  Examine the result for an exception.
    Memo1.Lines.Add(CkJsonObject__emit(result));

    //  Also examine the LastErrorText.
    Memo1.Lines.Add(CkJs__lastErrorText(js));
    Exit;
  end;

Memo1.Lines.Add(CkJsonObject__emit(result));

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

retval := CkJsonObject__stringOf(result,'value');
Memo1.Lines.Add(retval);

//  Output:
//  Hello, Michael!

CkStringBuilder_Dispose(sbScript);
CkJs_Dispose(js);
CkJsonObject_Dispose(result);
CkJsonObject_Dispose(funcCall);