SOLID / DRY principles

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In software development, Object-Oriented Design plays a crucial role when it comes to writing flexible, scalable, maintainable, and reusable code. There are so many benefits of using OOD but every developer should also have the knowledge of the SOLID principle for good object-oriented design in programming. The SOLID principles are designed to help developers design robust, maintainable applications. The five SOLID principles are: Single-responsibility principle - Function and classes should have one job. Open–closed principle - Classes and functions should be open for  extension but not for modification. Liskov substitution principle - Child class can replace parent class Interface segregation principle - This principle is the first principle that applies to Interfaces instead of classes in SOLID and it is similar to the single responsibility principle. It states that “do not force any client to implement an interface which is irrelevant to them“. Here your main goal is ...
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Currying in Javascript

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Currying is a technique in functional programming where a function is transformed into a sequence of nested functions, each taking a single argument. This allows you to partially apply arguments to a function and create new functions with some of the arguments pre-filled. Here's an example of currying in JavaScript:

function add(a) {
  return function(b) {
    return a + b;
  };
}

const add5 = add(5);
console.log(add5(3)); // Output: 8
console.log(add5(7)); // Output: 12


In this example, the `add` function takes one argument `a` and returns another function that takes a single argument `b` and returns the sum of `a` and `b`. By calling `add(5)`, we create a new function `add5` that adds 5 to its argument. Subsequently, calling `add5(3)` and `add5(7)` will add 5 to 3 and 7, respectively, resulting in the expected outputs.

Currying allows for a more flexible and reusable way of creating specialized functions. It enables you to partially apply arguments and create specialized versions of a function tailored to specific use cases.



Currying in JavaScript provides several benefits and can be useful in various scenarios. Here's a real-time example that demonstrates the need for currying:

Consider a function `calculateTotalPrice` that calculates the total price of a product based on its quantity and unit price:

function calculateTotalPrice(quantity, unitPrice) {
  return quantity * unitPrice;
}

console.log(calculateTotalPrice(2, 10)); // Output: 20


Now, let's say we have multiple products with fixed quantities but varying unit prices. Instead of repeatedly passing the quantity for each calculation, we can use currying to create a specialized function for each product's quantity:


function calculateTotalPrice(quantity) {
  return function(unitPrice) {
    return quantity * unitPrice;
  };
}

const calculateTotalPriceWithQuantity2 = calculateTotalPrice(2);
console.log(calculateTotalPriceWithQuantity2(10)); // Output: 20

const calculateTotalPriceWithQuantity5 = calculateTotalPrice(5);
console.log(calculateTotalPriceWithQuantity5(10)); // Output: 50


In this example, by currying the `calculateTotalPrice` function, we create two specialized functions: `calculateTotalPriceWithQuantity2` and `calculateTotalPriceWithQuantity5`. Each of these functions is pre-filled with a specific quantity (2 and 5, respectively). Now, when we invoke these specialized functions with the unit price, they return the total price for the corresponding quantity.

The advantages of using currying in this scenario are:
1. **Code Reusability**: We can create specialized functions for different quantities without duplicating the logic of calculating the total price.
2. **Partial Application**: By pre-filling the quantity, we create functions that require only the unit price as input, making it easier to reuse them in various contexts.

Currying is particularly beneficial when you have functions with multiple arguments and want to create reusable and specialized versions based on specific parameters. It helps in creating more modular, flexible, and composable code.

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