How to use namespace in managed lightning components

NamespaceDemoComp.html

<aura:component controller="NamespaceDemoCompController" implements="force:appHostable,flexipage:availableForRecordHome,force:hasRecordId" access="global" >
	<aura:handler name="init" value="{!this}" action="{!c.doInit}"/>
    <aura:attribute name="namespace" type="String"/>	
    <aura:attribute name="totalAmount" type="Decimal"/>
    Total Amount : {!v.totalAmount}
</aura:component>

NamespaceDemoCompController.cls

public class NamespaceDemoCompController {   
    
    public NamespaceDemoCompController() {}
    
    @AuraEnabled
    public static String getNamespaceName() { 
        
        String nameSpacePrefix;
        ApexClass cs =[select NamespacePrefix from ApexClass where Name ='NamespaceDemoCompController'];
        if(cs.NamespacePrefix != null){
            nameSpacePrefix = cs.NamespacePrefix+'__';
        }
        else{
            nameSpacePrefix = '';
        }
        
        return nameSpacePrefix;
    }
    
    @AuraEnabled
    public static List<Expense__c> getExpenses() {
        
        return [SELECT Id,Name, Client__c, Date__c, Amount__c FROM Expense__c ];
    } 
}

NamespaceDemoCompController.js

({
    doInit : function(component, event, helper) {
    	//call apex class method
    	var action = component.get('c.getNamespaceName');
    	action.setCallback(this,function(response){
        	//store state of response
   			var state = response.getState();
        	if (state === "SUCCESS") {
       			//set response value in namespace attribute on component
				component.set('v.namespace', response.getReturnValue());
                helper.getTotalAmount( component );
        	}
        });
		$A.enqueueAction(action);
    },
    
})

NamespaceDemoCompHelper.js

({
  // Fetch the expenses from the Apex controller
  // Calculate total amount here, it's just for demo purpose where we can see the use of namespace
  getTotalAmount: function(component) {
    var action = component.get('c.getExpenses');

    // Set up the callback
    var self = this;
    action.setCallback(this, function(actionResult) {
        let expenseList = actionResult.getReturnValue();
        let totalAmount = 0;
        let namespace = component.get('v.namespace');
        for(let i=0; i<expenseList.length; i++ ) {
        	totalAmount += expenseList[i][namespace + 'Amount__c'];  
        }
        component.set('v.totalAmount', totalAmount);
    });
    $A.enqueueAction(action);
  }
})