Search in Array in JavaScript

1// Method 1: Using indexOf
2let arr = [10, 20, 30, 40, 50];
3let searchValue = 30;
4
5let index = arr.indexOf(searchValue);
6if (index !== -1) {
7    console.log(`${searchValue} found at index ${index}`);
8} else {
9    console.log(`${searchValue} not found`);
10}
11
12// Method 2: Using includes
13let numbers = [5, 10, 15, 20, 25];
14console.log("\nUsing includes:");
15console.log("15 exists:", numbers.includes(15));
16console.log("35 exists:", numbers.includes(35));
17
18// Method 3: Using find
19let users = [
20    { id: 1, name: "John" },
21    { id: 2, name: "Jane" },
22    { id: 3, name: "Bob" }
23];
24
25let user = users.find(u => u.id === 2);
26console.log("\nUsing find:", user);
27
28// Method 4: Using findIndex
29let index2 = users.findIndex(u => u.name === "Bob");
30console.log("\nFindIndex:", index2);
31
32// Method 5: Using for loop
33function searchArray(arr, value) {
34    for (let i = 0; i < arr.length; i++) {
35        if (arr[i] === value) {
36            return i;
37        }
38    }
39    return -1;
40}
41
42console.log("\nUsing loop:", searchArray([1, 2, 3, 4, 5], 3));
43
44// Method 6: Binary search (sorted array)
45function binarySearch(arr, target) {
46    let left = 0;
47    let right = arr.length - 1;
48    
49    while (left <= right) {
50        let mid = Math.floor((left + right) / 2);
51        
52        if (arr[mid] === target) {
53            return mid;
54        } else if (arr[mid] < target) {
55            left = mid + 1;
56        } else {
57            right = mid - 1;
58        }
59    }
60    return -1;
61}
62
63let sorted = [1, 3, 5, 7, 9, 11, 13];
64console.log("\nBinary search:", binarySearch(sorted, 7));
65
66// Method 7: Using some (check existence)
67let hasEven = [1, 3, 5, 7, 8].some(num => num % 2 === 0);
68console.log("\nHas even number:", hasEven);