Easy explanation of currying【JS】
I’ve learned currying this week, so I’ll take a note.
What is currying?
In short, it is “deleting duplicated codes by using a function that return a function ”. Knowing examples is easier than getting examination, so I’ll show an example.
//currying
const add = x => y => x + y
add(3)(5)
//=> 8This is currying. It is different from a normal arrow function.
//normal arrow function
const add = (x, y) => x + y
add(3, 5)
//=> 8In case of currying, firstly, when add(3) is executed, ‘ y => x + y ’ is returned. It returns the function, and when ‘(5)’ is added, ‘ y ’ becomes ‘ 5 ’, so 8 is returned. You can see this flow with “console.log”.
What is a merit?
If you’ll use this technique, what good thing will happen? It is “deleting duplicated programmes”. The difference between normal arrow function and currying is below.
//normal arrow function
const add = (x, y) => x + yadd(1, 2) //=> 3
add(1, 4) //=> 5
add(1, 7) //=> 8//add(1) is duplicated, it is not good!//currying
const add = x => y => x + y
const add1 = add(1)const add1(2) //=> 3
const add1(4) //=> 5
const add1(7) //=> 8//duplicated programmes are deleted, so it is good!
This is the merit of using currying.
Wrap up
I think currying is not so difficult, and useful. I recommend this.
