filter by index javascript code example

Example 1: who to accses to an object vallue inside an array with .filter method js

const array = [
  {
    username: "john",
    team: "red",
    score: 5,
    items: ["ball", "book", "pen"]
  },
  {
    username: "becky",
    team: "blue",
    score: 10,
    items: ["tape", "backpack", "pen"]
  },
  {
    username: "susy",
    team: "red",
    score: 55,
    items: ["ball", "eraser", "pen"]
  },
  {
    username: "tyson",
    team: "green",
    score: 1,
    items: ["book", "pen"]
  },

];
//FILTER MEMBERS IN TEAM "RED"
const filterArray=array.filter(word=>word.team==="red")

Example 2: how the filter() function works javascript

const arr = [1, 2, 3, 4, 5, 6, 7, 8, 9];

const filter = arr.filter((number) => number > 5);
console.log(filter); // [6, 7, 8, 9]

Example 3: javascript object filter

function objectFilter = (obj, predicate) => 
    Object.keys(obj)
          .filter( key => predicate(obj[key]) )
          .reduce( (res, key) => (res[key] = obj[key], res), {} );

// Example use:
var scores = {
    John: 2, Sarah: 3, Janet: 1
};

var filtered = objectFilter(scores, num => num > 1); 
console.log(filtered);

Example 4: array.filter in js

var numbers = [1, 3, 6, 8, 11];

var lucky = numbers.filter(function(number) {
  return number > 7;
});

Example 5: array.filter in javascript

//Eg 1 - If item is unchecked, remove it from array

const array = [2, 3, 4]

if (event.target.checked) {
      newValue.push(option);
    } else {
      newValue = newValue.filter(item => item.id != option.id);
    }

//If false, it will remove the element. 2 is not equal to 2.

//Eg 2 - To return an array with length > 6

const words = ['spray', 'limit', 'elite', 'exuberant', 'destruction', 'present'];
const result = words.filter(word => word.length > 6);

Example 6: js filter items by index

let newArray = arr.filter(callback(element[, index, [array]])[, thisArg])