How to refactor to a higher order function?-CodePudding

How to refactor this function to a higher order function?

It is meant to return a new array containing the sub-arrays of characters that contain the value 'Rambo'.

function isRamboCharacter(characters) {

 const x = [];

  for (let i = 0; i < characters.length; i  ) {
    if (characters[i].movie.includes('Rambo')) {
      x.push(characters[i]);
    }
  }

return x;
}

I tried:

return characters.movie.includes('Rambo');

CodePudding user response：

Solution

const characters = [
    { movie: ["Rambo", "Rockey", "Avengers"] }, 
    { movie: ["Fatherhood", "Rockey", "Avengers"] }
 ]
    
const isRamboCharacter = (characters) => characters.filter((char) => char.movie.includes("Rambo"))

console.log(isRamboCharacter(characters));

Or you could directly call Array's filter method

console.log(characters.filter((char) => char.movie.includes("Rambo")));

//output - [ { movie: [ 'Rambo', 'Rockey', 'Avengers' ] } ]

CodePudding user response：

You can curry it (Return a function in a function)

function isCharacterInMovie(movie) {
  return function filterFunction(characters) {
    const x = [];
    for (let i = 0; i < characters.length; i  ) {
      if (characters[i].movie.includes(movie)) {
        x.push(characters[i]);
      }
    }
    return x;
  }
}
const isRamboInMovie = isCharacterInMovie('rambo') // returns the inner function which holds on to the value from when you called it
 isRamboInMovie(charactersInTheMatrix); // []
 isRamboInMovie(charactersInRambo); // ['rambo']

The 'You don't know JS' book series has a great (short AND free) book on this, and it explains it incredibly well You Don't Know JS Yet: Scope & Closures - 2nd Edition