JavaScript - Search An Item in an Array

Here are the different methods to search for an item in an array in JavaScript

1. Using indexOf()

The indexOf() method searches for a specified value in an array and returns its first index. If the value is not found, it returns -1.

const a = [10, 20, 30, 40];

const index = a.indexOf(30);
console.log(index);

const notFound = a.indexOf(50);
console.log(notFound);

2
-1

This method works well for primitive data types like numbers or strings but doesn't work for objects.

2. Using includes()

The includes() method checks if an array contains a specific value and returns a boolean (true or false).

const a = [5, 10, 15, 20];

console.log(a.includes(15));
console.log(a.includes(25)); 

true
false

This method is simple and best used when you only need to know if an item exists.

3. Using find()

The find() method searches for an item in an array based on a condition defined in a callback function. It returns the first matching element or undefined if no match is found.

const a = [
    { id: 1, value: 100 },
    { id: 2, value: 200 },
    { id: 3, value: 300 },
];

const res = a.find((item) => item.id === 2);
console.log(res);

{ id: 2, value: 200 }

This is ideal for arrays of objects when you need to find an item based on a specific property.

4. Using filter()

The filter() method is used to find all elements in an array that match a condition. It returns an array of matching elements.

const a = [
    { id: 1, value: 50 },
    { id: 2, value: 100 },
    { id: 3, value: 50 },
];

const res = a.filter((item) => item.value === 50);
console.log(res); 

[ { id: 1, value: 50 }, { id: 3, value: 50 } ]

Use this method when you expect multiple matches.

5. Using some()

The some() method checks if at least one element in the array satisfies a condition. It returns true if a match is found and false otherwise.

const a = [10, 20, 30, 40];
const hasValue = a.some((item) => item > 25);
console.log(hasValue);

true

This method is useful when you only need to check for the existence of a match.

6. Using findIndex()

The findIndex() method works similarly to find() but returns the index of the first matching element instead of the element itself. If no match is found, it returns -1.

const a = [
    { id: 1, name: "X" },
    { id: 2, name: "Y" },
    { id: 3, name: "Z" },
];

const index = a.findIndex((item) => 
	item.id === 2);
console.log(index);

1

This is helpful when you need the index of the matching element.

7. Using for-of Loop

The for-of loop is another manual approach to search for an item in an array.

const a = [100, 200, 300];
let found = false;

for (const item of a) {
    if (item === 200) {
        found = true;
        break;
    }
}

console.log(found);

true

This method is more readable than the traditional for loop.