ECMAScript allows usage of const to define constants in JavaScript. To define integer constants in JavaScript, use the const,
const MY_VAL = 5; // This will throw an error MY_VAL = 10;
As shown above, MY_VAL is a constant and value 5 is assigned. On assigning, another value to a constant variable shows an error.
Using const will not allow you to reassign any value to MY_VAL again. If you will assign a new value to a constant, then it would lead to an error.