Constants in Redux help us in easily finding all the usages of a particular functionality across our entire project when we are using an Integrated Development Environment (IDE).
Using constants, we can avoid silly bugs caused because of typing errors or typos as it shows a "ReferenceError" whenever a typo is made.
export const ADDING_TODO = 'ADDING_TODO';
export const DELETING_TODO = 'DELETING_TODO';
export const EDITING_TODO = 'EDITING_TODO';
export const COMPLETING_TODO = 'COMPLETING_TODO';
export const COMPLETING_ALL = 'COMPLETING_ALL';
export const CLEARING_COMPLETED = 'CLEARING_COMPLETED';