Calling Apex method at regular interval from Lightning Component

IntervalJS.cmp

<aura:component implements="force:appHostable,flexipage:availableForAllPageTypes,flexipage:availableForRecordHome,force:hasRecordId,forceCommunity:availableForAllPageTypes,force:lightningQuickAction" controller="RefreshContactCounter" access="global" >
	
    <aura:attribute name="recordId" type="Id"></aura:attribute>
    <aura:attribute name="pollId" type="String"></aura:attribute>

    <lightning:button variant="brand" label="Subscribe" title="Subscribe" onclick="{!c.init}" />
    <lightning:button variant="brand-outline" label="Stop" title="Stop" onclick="{!c.cancelSubscribe}" />
      
</aura:component>

IntervalJS.helper

({
    checkSubscribeCall: function(component, event, helper){
        
       //execute callApexMethod() again after 5 sec each
        var pollId = window.setInterval(
            $A.getCallback(function() { 
                // Calling Apex Method
                helper.callApexMethod(component,helper,pollId);
            }), 5000
        );  
        
    },
                           
    handleResponse : function (response, component){
        var retVal = response.getReturnValue() ;
        // Your Logic
    },
        
    callApexMethod : function (component,helper,pollId){
        // Setting current pollId to stop the loop
       	component.set('v.pollId', pollId);
        // Setting Apex Method
        var action = component.get("c.getContactCount");
        // Setting Apex Param
        action.setParams({ Id : component.get("v.recordId") });
        // Call Back Action
        action.setCallback(this, function(response) {
            this.handleResponse(response, component);
        });
        $A.enqueueAction(action); 
    } 
})

IntervalJS.js

({
    init : function(component, event, helper) {
		    // Calling Helper
        helper.checkSubscribeCall(component, event,helper);
	},
    
    cancelSubscribe : function (component, event, helper){
        window.clearInterval(component.get('v.pollId'));
    }
})

RefreshContactCounter.cls

public class RefreshContactCounter {
    
    @AuraEnabled
    public static Integer getContactCount(){
         AggregateResult[] groupedResults = [SELECT count(Id) totalCount FROM Contact];
		Object totalCount = groupedResults[0].get('totalCount');
        return (Integer) totalCount ;
    }

}