Javascript Promise.all : Way to perform action when Multiple Parallel enqueued Actions are Completed

SK_promiseAllDemo.cmp

<aura:component controller="SK_PromiseAllDemoController">
    <aura:attribute name="ltngAccList" type="List"/>
    <aura:attribute name="ltngTaskList" type="List"/>
    
    <aura:attribute name="ltngOperationInfoString" type="String" default=""/>
    
    <div  style="text-align: center;background-color:#E6E6FA;border-style: solid;margin:10px;">
        <lightning:button label="Fetch Accounts/Task records parallelly" onclick="{!c.findDataUsingPromise}"/>
    </div>
    
    <aura:if isTrue="{!v.ltngOperationInfoString=='DONE'}">
        
        <aura:if isTrue="{!!empty(v.ltngAccList)}">
            <div style="background-color:#E6E6FA;border-style: solid;margin:5px;">
                <table class="slds-table slds-table_fixed-layout slds-table_bordered slds-table_cell-buffer">  
                    <thead> 
                        <tr class="slds-text-title--caps"> 
                            <th scope="col">Name</th> 
                            <th scope="col">Type</th> 
                            <th scope="col">Industry</th>
                        </tr> 
                    </thead> 
                    <tbody> 
                        <aura:iteration items="{!v.ltngAccList}" var="item"> 
                            <tr class="slds-hint-parent"> 
                                <td scope="row"> {!item.Name}</td> 
                                <td > {!item.Type}</td> 
                                <td > {!item.Industry}</td>
                            </tr> 
                        </aura:iteration> 
                    </tbody> 
                </table>
            </div>
        </aura:if>
        <br/>
        <aura:if isTrue="{!!empty(v.ltngTaskList)}">
            <div style="background-color:#E6E6FA;border-style: solid;margin:5px;">
                <table class="slds-table slds-table_fixed-layout slds-table_bordered slds-table_cell-buffer">  
                    <thead> 
                        <tr class="slds-text-title--caps"> 
                            <th scope="col">Subject</th> 
                            <th scope="col">Status</th> 
                            <th scope="col">Description</th>
                        </tr> 
                    </thead> 
                    <tbody> 
                        <aura:iteration items="{!v.ltngTaskList}" var="item"> 
                            <tr class="slds-hint-parent"> 
                                <td scope="row"> {!item.Subject}</td> 
                                <td > {!item.Status}</td> 
                                <td > {!item.Description}</td>
                            </tr> 
                        </aura:iteration> 
                    </tbody> 
                </table>
            </div>
        </aura:if>
        
    </aura:if>
    
    <aura:if isTrue="{!v.ltngOperationInfoString=='WAITING'}">
        <div style="background-color:#E6E6FA;border-style: solid;margin:5px;">
            <b>Waiting for response for both server calls to get Account Information and Task Information</b>
        </div>
    </aura:if>
</aura:component>

SK_PromiseAllDemoApp.app

<aura:application extends="force:slds">
  <c:SK_PromiseAllDemo/>
</aura:application>

SK_PromiseAllDemoController.cls

public class SK_PromiseAllDemoController {
	@AuraEnabled
    public static List<Account> findMyAccounts(integer numberOfRecords){
        return [select id,Name,Type,Industry from Account where createdById=:UserInfo.getUserId() order by LastModifieddate DESC Limit :numberOfRecords];
    } 
    @AuraEnabled
    public static List<Task> findMyPendingTasks(integer numberOfRecords){
        return [select id,Description,Status,Subject from Task where OwnerId=:UserInfo.getUserId() order by LastModifieddate DESC Limit :numberOfRecords ];
    }
}

SK_promiseAllDemoController.js

({
    findDataUsingPromise : function (component,event,helper){
        console.log('****inside findDataUsingPromise');
        component.set("v.ltngOperationInfoString","WAITING");
        var accList=component.set("v.ltngAccList",[]);
        var accList=component.set("v.ltngTaskList",[]);
        var params={"numberOfRecords":3};
        var promise1 = helper.ServerCallUsingPromise(component,'c.findMyAccounts',params);
        var promise2 = helper.ServerCallUsingPromise(component,'c.findMyPendingTasks',params);
        //create array of promise
        var promiseArray =[promise1, promise2];
        var combinedPromise = Promise.all(promiseArray);
        combinedPromise
        .then($A.getCallback(function(results){
            //handle success
            var accResults = results[0]; //Results from Promise 1
            var taskResults = results[1]; //Results from Promise 2
			component.set("v.ltngAccList", accResults);
            component.set("v.ltngTaskList", taskResults);
            component.set("v.ltngOperationInfoString","DONE");
        })) 
        .catch($A.getCallback(function () { 
            console.log('Some error has occured'); 
        }));
    } 
})

SK_promiseAllDemoHelper.js

({
    callToServer : function(component, method, callback, params) {
        var action = component.get(method);
        if(params){
            action.setParams(params);
        }
        console.log('****param to controller:'+JSON.stringify(params));
        action.setCallback(this, function(response) {
            var state = response.getState();
            if (state === "SUCCESS") {
                callback.call(this,response.getReturnValue());
            }else if(state === "ERROR"){
                var errors = response.getError();
                console.error(errors);
                alert('Problem with connection.'+errors);
            }
        });
        $A.enqueueAction(action);
    },
    ServerCallUsingPromise : function( component,method, params ) {
        var promiseInstance = new Promise( $A.getCallback( function( resolve , reject ) { 
            var action = component.get(method);
            if(params){
                action.setParams(params);
            }
            console.log('****param to controller:'+JSON.stringify(params));
            action.setCallback(this, function(response) {
                var state = response.getState();
                if (state === "SUCCESS") {
                    resolve(response.getReturnValue());
                }else if(state === "ERROR"){
                    var errors = response.getError();
                    console.error(errors);
                    reject(response.getError() );
                }
            });
            $A.enqueueAction(action);
        }));            
        return promiseInstance;
    }
})