追加到字符串Ramda.js的末尾

Question

I am trying to append a string to the end of a string using Ramda, but the following does not work.

R.append("A", "B")

it returns

['A','B']

Does anybody know a good way to do this in Ramda or in a way that does not mean I need to write code to curry javascripts concat function?

Edit:

I am trying to do the following

 props = { city: "Boston", state: "Massachusetts", zip: 22191 } var appendCommaToCity = R.evolve({city: R.append(",")} appendCommaToCity(props) 

Doing "A" + "B" does not work in this sitchuation unless I define the function somewhere else and curry it, or define it inline.

Answer 1

As others have pointed out, concat is the simplest approach, using either of these techniques:

const appendCommaToCity = R.evolve({city: R.concat(R.__, ",")})
// or 
const appendCommaToCity = R.evolve({city: R.flip(R.concat)(",")})

The first one, using the placeholder might be easier here.

But I'm guessing that your result is an intermediate structure that will later be used to join that city with the state. If that's the case, then this might be overkill. It's simply too easy at least in modern JS, to combine them directly:

const foo = ({city, state}) => `${city}, ${state}`

You can see this all in action in the Ramda REPL .

Answer 2

console.log(R.concat("ACD", "BEF")); // concatenates strings as they are
// => ACDBEF
// Or
var arr = R.append("ACD", "BEF"); // creates array ["B","E","F","ACD"]
var last = [arr.pop()]; // gets the last element "ACD" and removes it from the array
console.log(last.concat(arr).join('')); // adds the last to the beginning of the array then joins all to form a string
// => ACDBEF
// Or
console.log("ACD" + "BEF"); // simple js string addition
// => ACDBEF
// ++ There are more js methods

Answer 3

 console.log("A".concat("B").concat("C")) console.log("".concat("A", "B", "C")) console.log(String.prototype.concat("A", "B", "C")) 

But just "A" + "B" is a lot faster than concat