partial-application is a technique of producing another function from defined function by fixing a number of arguments in the defined function.
you can do this by the built in method .bind or with currying technique :
.bind method
function add(x, y) { return x + y; }
// Function.prototype.bind
const addOne = add.bind(null, 1);
addOne(2); // 3
// arrow functions
const addTen = x => add(x, 10);
addTen(2); // 12
currying technique
const add = x => y =>x+y
// currying
const addOne = add( 1);
addOne(2); // 3
// seconde example
const addTen = x => add(10);
addTen(2); // 12
However, there are several of limitations with these approaches:
-1- .bind methode require you explicitly specify the this receiver
-2- currying technique may cause callback hell
To resolve these concerns, javascript introduce new language features :
A new calling convention,
~(), to indicate a partial application of a call or new expression which results in a partially applied function.Using the
?token to act as a placeholder argument for any non-fixed argument in a partial application.
const add = (x, y) => x + y;
// apply from the left:
const addOne = add~(1, ?);
addOne(2); // 3
// apply from the right:
const addTen = add~(?, 10);
addTen(2); // 12
This proposal is currently on stage 1 , if you wanna more details you can find them here : l[github.com/tc39/proposal-partial-applicatio..
enjoy !!