How to wait for a response from 3 glideajax asynchronous calls within a client script, and then continue with the rest code?

[Smith Johnson]

Hello,

I have a catalog client script where I make three glideajax calls (asynchronous). 

            var ga1=new GlideAjax("PUtilsAjax");
		ga1.addParam("sysparm_name", "region1");
		ga1.addParam("sysparm_vs_token", token);
		ga1.getXML(callback1);
	
	    var ga2=new GlideAjax("PUtilsAjax");
		ga2.addParam("sysparm_name", "region2");
		ga2.addParam("sysparm_vs_token", token);
		ga2.getXML(callback2);
	
	    var ga3=new GlideAjax("PUtilsAjax");
		ga3.addParam("sysparm_name", "region3");
		ga3.addParam("sysparm_vs_token", token);
		ga3.getXML(callback3);
		   
	
		function callback1(response){
			var answerStr = response.responseXML.documentElement.getAttribute("answer");
			var ans = JSON.parse(answerStr);
			console.log("answer region1");
			console.log(ans);
		}
	
		function callback2(response){
			var answerStr = response.responseXML.documentElement.getAttribute("answer");
			var ans = JSON.parse(answerStr);
			console.log("answer region2");
			console.log(ans);
		}
	
		function callback3(response){
			var answerStr = response.responseXML.documentElement.getAttribute("answer");
			var ans = JSON.parse(answerStr);
			console.log("answer rehion3");
			console.log(ans);
		}

                // I want the logic below to be executed ONLY IF I have the responses from the three asynchronous glide ajax calls

                // some logic ++

My first question is: Are these calls in reality asynchronous?? Because even if the third call lasts 3 sec and the first call lasts 20 sec, the third callback is executed after the first one. Do I miss something here?

My second question is: How I can execute some logic ONLY IF I have the responses from the three asynchronous calls??


I would be grateful for your assistance.

Smith.

[Hitoshi Ozawa]

Agree with Maik that ServiceNow client script aren't executing in parallel.

I'll create multiple events and have multiple script actions to handle each event.

[Hitoshi Ozawa]

FYI, async calls are call asynchronously but the response object from these calls are blocking making each call in serial instead of parallel.

[Smith Johnson]

Thank you @Hitoshi Ozawa , I didn't know that. This was helpful.

Regarding your comment with multiple events, what's the logic?

1) Can I trigger such events from client-script or I guess from script include? After the trigger of the four events, I don't want to execute the rest code. I need to take the 4 responses and aggregate them in an array to be able to continue further with the rest code. Can I do so in my script include ( I mean to wait ) ???

2) For example, I trigger 4 different events from my script include. Then I have 4 different script actions (based on the trigger of each event). Are they going to be executed in parallel?

3) When each of the script actions is completed and a response is received. Can the script action sent back to my script include the response?

Thank you in advance. Your answers might be really helpful.