Source Code : test_gameSettings.html

<script type="text/javascript"> 
<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Όνομα Ζώο Φυτό - Το παιχνίδι </title>
    <script src="tests_pretty.js"></script>
</head>
<body>
Example :
<mark>Services Word Games</mark>
<br/> <br/>
<script>
    displayInfo(" api :  " + URL, null, 'url');
    let sPlugin = "gameSettings";
    let gameDBPin = null;
    let gameDBMaterKey = null;
    // action = create
    let data = {
	        "configuration": [sPlugin, 'create', ""],
	        'pin': '',
	        'description': 'new game - info - client '
	};
    fetch(URL, {
	        method: "POST",
	        body: JSON.stringify(data),
	        headers: {
		            "Content-type": "application/json;
		 charset=UTF-8"
		}
	}).then(response => response.json())
        .then(dataRet => {
	            displayInfo("  Service Call   ", data, 'retCall');
	            let returnJSON = dataRet;
	            gameDBPin = returnJSON.pin;
	            gameDBMaterKey = returnJSON.masterKey;
	      // Administration
	            displayInfo(sPlugin + "  Returns Json  ", returnJSON, 'retInfo');
	            //  *********************** close gamec - GAMEOVER
	            //   several call API   with -- serviceCoreData
	            // action = terminate
	            serviceCoreData(URL, {
		                "configuration": [sPlugin, 'play', ''],
		                'pin': gameDBPin,
		})
	                .then(data => {
		                    displayInfo("  info  play ", data, 'infoplay');
		});
	            serviceCoreData(URL, {
		                "configuration": ["playerSettings", 'create', ''],
		                'pin': gameDBPin,
		                'nickname': 'testingPlayer'
		})
	                .then(data => {
		                    displayInfo("  Game PIN "+ gameDBPin + " joined NEW player  testingPlayer " , data, 'playersss');
		});
	            var characters       = 'ΑΒΓΔΕΖΗΘΙΚΛΜΝΞΟΠΡΣΤΥΦΧΨΩ';
	            var charactersLength = characters.length;
	            var  startL = characters.charAt(Math.floor(Math.random() *        charactersLength));
	            serviceCoreData(URL, {
		                "configuration": ['gameSettings', 'playLetter', ''],
		                'pin': gameDBPin,
		                'letter': startL,
		})
	                .then(data => {
		                    displayInfo("  Play with Letter   ", data, 'playnasow');
		});
	            serviceCoreData(URL, {
		                "configuration": [sPlugin, 'info', ''],
		})
	                .then(data => {
		                    displayInfo("  info  ", data, 'informartaion');
		});
	            serviceCoreData(URL, {
		                "configuration": [sPlugin, 'terminate', ''],
		                'pin': gameDBPin,
		})
	                .then(data => {
		                    displayInfo("  Terminate Game  ", data, 'terminate');
		});
	            serviceCoreData(URL, {
		                "configuration": [sPlugin, 'getPlayers', ''],
		                'pin': gameDBPin,
		})
	                .then(data => {
		                    displayInfo("  getPlayers    ", data, 'terminatdse');
		});
	})
        .catch((error) => {
	            displayInfo(" Error : " + error, data);
	});
</script>
</body>
</html>
</script>

Typical Syntax Call

<script type="text/javascript"> 

    let URL = 'https://xxx.xxx.xxx.xxx/service.php'
    let sPlugin = "plugin";
    //
    const data = {  "configuration": [sPlugin, "action", "extra"],
	                    'word': ' Απόδειξη ',
	};
    //
    fetch(URL, {    method: "POST",   body: JSON.stringify(data),
	headers: {   "Content-type": "application/json;
		 charset=UTF-8"    
		}
	}).then(response => response.json())
        .then(dataRet => {
	            const returnJSON = JSON.parse(dataRet);
	             // returnJSON  
	             // ....
	             ///
	})
        .catch((error) => {
	            displayInfo(" Error : " + error, data);
	});

</script>