How to Search an Array in JavaScript | ninjasquad
In this tutorial, we’ll learn how to search elements in an Array using different Array methods in JavaScript.
Array.filter()
Array.filter() method takes a condition as a function and return an array of elements satisfying that condition.
Example 1
const array = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10];
const allEvenNumbers = array.filter(n => n%2==0); // [2, 4, 6, 8, 10]
const allOddNumbers = array.filter(n => n%2==1); // [1, 3, 5, 7, 9]
const greaterThanNine = array.filter(n => n>9); // [10]
Example 2
const fruits = [
{ name: "mango", color: "yellow", calories: 135},
{ name: "banana", color: "yellow", calories: 60 },
{ name: "apple", color: "red", calories: 65 },
{ name: "orange", color: "orange", calories: 50 },
{ name: "kiwi", color: "green", calories: 46 },
];
const yellowFruits = fruits.filter(fruit => fruit.color == "yellow").map(fruit => fruit.name); // ["mango", "banana"]
const lowCalories = fruits.filter(fruit => fruit.calories <=50).map(fruit => fruit.name); // ["orange", "kiwi"]
Array.find()
Array.find() method takes a condition as a function and return the first element satisfying that condition.
Example 1
const array = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10];
const allEvenNumbers = array.find(n => n%2==0); // 2
const allOddNumbers = array.find(n => n%2==1); // 1
const greaterThanNine = array.find(n => n>9); // 10
Example 2
const fruits = [
{ name: "mango", color: "yellow", calories: 135},
{ name: "banana", color: "yellow", calories: 60 },
{ name: "apple", color: "red", calories: 65 },
{ name: "orange", color: "orange", calories: 50 },
{ name: "kiwi", color: "green", calories: 46 },
];
const yellowFruits = fruits.find(fruit => fruit.color == "yellow");
console.log(yellowFruits); // prints {name: "mango", color: "yellow", calories: 135}
const lowCalories = fruits.find(fruit => fruit.calories <=50);
console.log(lowCalories); // prints {name: "orange", color: "orange", calories: 50}
Array.includes()
Array.includes() method look for the given value and return true if find in the array, otherwise return false.
Example 1
const array = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10];
const includesTen = array.includes(10); // true
const includesTwenty = array.includes(20); // false
Example 2
const fruits = [
{ name: "mango", color: "yellow", calories: 135},
{ name: "banana", color: "yellow", calories: 60 },
{ name: "apple", color: "red", calories: 65 },
{ name: "orange", color: "orange", calories: 50 },
{ name: "kiwi", color: "green", calories: 46 },
];
const includesMango = fruits.map(fruit => fruit.name).includes("mango"); // true
const includesBlue = fruits.map(fruit => fruit.color).includes("blue"); // false
Example 3
Count the number of vowels in a given string:-
const vowels = ['a', 'e', 'i', 'o', 'u'];
const string = "codingnconcepts";
const countVowels = word.split("").map(char => vowels.includes(char) ? 1 : 0).reduce((a, b) => a + b);
console.log(countVowels); // prints "4"
Array.indexOf()
Array.indexOf() method look for the given value and return index if find in the array, otherwise return -1.
Example 1
const array = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10];
const indexOfTen = array.indexOf(10); // 9
const indexOfTwenty = array.indexOf(20); // -1
Example 2
const fruits = [
{ name: "mango", color: "yellow", calories: 135},
{ name: "banana", color: "yellow", calories: 60 },
{ name: "apple", color: "red", calories: 65 },
{ name: "orange", color: "orange", calories: 50 },
{ name: "kiwi", color: "green", calories: 46 },
];
const indexOfMango = fruits.map(fruit => fruit.name).indexOf("mango"); // 0
const indexOfBlue = fruits.map(fruit => fruit.color).indexOf("blue"); // -1
Source: Internet