# javascript compose function

## What is JavaScript Compose Function?

JavaScript Compose Function is a higher-order function that takes multiple functions as arguments and then returns a new function. This new function is composed of all the functions passed as arguments, and it can be called with a single argument that will flow through all the composed functions.

### How does it work?

When we pass multiple functions to Compose Function, it returns an inner function that accepts a single argument. This inner function will apply the rightmost function to the argument and pass the result to the next function in the chain. This process continues until all functions have been applied. Here's an example:

```
const add = (x) => x + 1;
const multiply = (x) => x * 2;
const composedFunction = compose(multiply, add);
composedFunction(2); // 6
```

In the above example, we have two functions - add and multiply. We pass both of them to Compose Function, which returns a new function that multiplies the result of add function by 2. Finally, we call the composedFunction with an argument of 2, and it returns 6.

### Multiple ways to implement Compose Function

There are multiple ways to implement Compose Function in JavaScript. Here are a few:

**Using reduce method:**We can use the reduce method to iterate over the functions and compose them into a single function.**Using functional programming:**We can use functional programming techniques like recursion and currying to implement Compose Function.**Using lodash library:**Lodash library provides a compose method that can be used to compose functions.

Here's an example of using reduce method to implement Compose Function:

```
const compose = (...functions) => {
return functions.reduce((f, g) => (...args) => f(g(...args)));
};
const add = (x) => x + 1;
const multiply = (x) => x * 2;
const composedFunction = compose(multiply, add);
composedFunction(2); // 6
```

In the above example, we define the compose function that takes multiple functions as arguments and returns a new function that composes all the functions. We use the reduce method to iterate over the functions and compose them into a single function.

### Conclusion

JavaScript Compose Function is a powerful tool that can simplify our code by allowing us to compose multiple functions into a single function. It can be implemented using various techniques like reduce method, functional programming, or external libraries like lodash. By mastering Compose Function, we can write more maintainable and reusable code.