I have found a script example, in it there is a line of code that looks something like this:
fn = (arg1) => (arg2) => {
//do something with arg1 and arg2
}
I am wondering exactly what is happening here, and how would it look as a "normal" function?
fn = (arg1) => (arg2) => {
//do something with arg1 and arg2
}
fn is a name for the first anon function
its basically a function that returns another function
it translated roughly to
var fn = function(arg1){
return function(arg2){
... // do something
}
}
noting that the this value will differ because it is an arrow function .
this?
thiswould refer to fn, whereas thisinside the return function in the second example will refer to the return function itself?It looks like two nested function, where the outer function returns the inner function with a closure over arg1.
var fn = function (arg1) {
return function (arg2) {
//do something with arg1 and arg2
};
};
var fn = function (arg1) {
return function (arg2) {
return arg1 + arg2;
};
};
var add4 = fn(4),
add20 = fn(20);
console.log(add4(5)); // 9
console.log(add20(5)); // 25An arrow function expression has a shorter syntax than a function expression and does not bind its own
this, arguments, super, or new.target. These function expressions are best suited for non-method functions, and they cannot be used as constructors.
this, do you know what it means?
I cannot add comments so I write this as an answer. Your example is also known as currying a concept that allows you to pass in a subset of arguments to a function and get a function back that’s waiting for the rest of the arguments.
I am wondering exactly what is happening here, and how would it look as a "normal" function? If you asked me that and I said it's also known as currying I'm pretty sure you'd give me a quizical look :) It's certainly correct, it's just it is a footnote to the actual answer - you should look at the upvoted answers here so see how they differ.