Array.prototype.filter()

const words = ["spray", "elite", "exuberant", "destruction", "present"];

const result = words.filter((word) => word.length > 6);

console.log(result);
// Expected output: Array ["exuberant", "destruction", "present"]

//  
filter((element) => { ... } )
filter((element, index) => { ... } )
filter((element, index, array) => { ... } )

// -
filter(callbackFn)
filter(callbackFn, thisArg)

//  -
filter(function callbackFn(element) { ... })
filter(function callbackFn(element, index) { ... })
filter(function callbackFn(element, index, array){ ... })
filter(function callbackFn(element, index, array) { ... }, thisArg)

function isBigEnough(value) {
  return value >= 10;
}

let filtered = [12, 5, 8, 130, 44].filter(isBigEnough);
//  filtered   [12, 130, 44]

const array = [-3, -2, -1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13];

function isPrime(num) {
  for (let i = 2; num > i; i++) {
    if (num % i == 0) {
      return false;
    }
  }
  return num > 1;
}

console.log(array.filter(isPrime)); // [2, 3, 5, 7, 11, 13]

let arr = [
  { id: 15 },
  { id: -1 },
  { id: 0 },
  { id: 3 },
  { id: 12.2 },
  {},
  { id: null },
  { id: NaN },
  { id: "undefined" },
];

let invalidEntries = 0;

function filterByID(item) {
  if (Number.isFinite(item.id) && item.id !== 0) {
    return true;
  }
  invalidEntries++;
  return false;
}

let arrByID = arr.filter(filterByID);

console.log(" \n", arrByID);
//  
// [{ id: 15 }, { id: -1 }, { id: 3 }, { id: 12.2 }]

console.log("   = ", invalidEntries);
//    = 5

var fruits = ["apple", "banana", "grapes", "mango", "orange"];

/**
 *        (query)
 */
function filterItems(query) {
  return fruits.filter(function (el) {
    return el.toLowerCase().indexOf(query.toLowerCase()) > -1;
  });
}

console.log(filterItems("ap")); // ['apple', 'grapes']
console.log(filterItems("an")); // ['banana', 'mango', 'orange']

const fruits = ["apple", "banana", "grapes", "mango", "orange"];

/**
 *        (query)
 */
const filterItems = (arr, query) => {
  return arr.filter(
    (el) => el.toLowerCase().indexOf(query.toLowerCase()) !== -1,
  );
};

console.log(filterItems(fruits, "ap")); // ['apple', 'grapes']
console.log(filterItems(fruits, "an")); // ['banana', 'mango', 'orange']

//   
let words = ["spray", "limit", "exuberant", "destruction", "elite", "present"];

const modifiedWords = words.filter((word, index, arr) => {
  arr[index + 1] += " extra";
  return word.length < 6;
});

console.log(modifiedWords);
//  ,       6,      ,
//    ['spray']

//   
words = ["spray", "limit", "exuberant", "destruction", "elite", "present"];
const appendedWords = words.filter((word, index, arr) => {
  arr.push("new");
  return word.length < 6;
});

console.log(appendedWords);
//     ,  `words`     ,
//   6 : ['spray', 'limit', 'elite']

//  
words = ["spray", "limit", "exuberant", "destruction", "elite", "present"];
const deleteWords = words.filter((word, index, arr) => {
  arr.pop();
  return word.length < 6;
});

console.log(deleteWords);
// ,  'elite'  ,     `words`  ,
//  filter   : ['spray', 'limit']