JavaScript Array Search

JavaScript arrays are commonly used to store lists of items, but we often need to search within arrays to locate specific values or elements that meet certain conditions. JavaScript provides several array search methods to help you find items easily, each with its own purpose and use case.

JavaScript Array Search Methods

1. indexOf()

The indexOf() method returns the first index of a specified element within an array. If the element is not found, it returns -1. This method is case-sensitive, meaning "Apple" and "apple" would be treated as different values.

Example:

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const fruits = ["Apple", "Banana", "Cherry", "Apple"];
let index = fruits.indexOf("Apple"); // Outputs: 0
let notFound = fruits.indexOf("Orange"); // Outputs: -1

2. lastIndexOf()

The lastIndexOf() method works like indexOf() but searches for the specified element from the end of the array, returning the last occurrence’s index. If the element is not found, it returns -1.

Example:

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const fruits = ["Apple", "Banana", "Cherry", "Apple"];
let lastIndex = fruits.lastIndexOf("Apple"); // Outputs: 3

3. includes()

The includes() method checks if an array contains a specified element and returns true or false. This method is useful for a quick check to see if an item exists in the array.

Example:

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const fruits = ["Apple", "Banana", "Cherry"];
let hasBanana = fruits.includes("Banana"); // Outputs: true
let hasOrange = fruits.includes("Orange"); // Outputs: false

Array Find Methods

4. find()

The find() method returns the first element in the array that satisfies a provided testing function. If no elements match the condition, it returns undefined. This method is especially useful for finding objects or complex data that meets specific criteria.

Example:

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const numbers = [5, 12, 8, 130, 44];
let found = numbers.find(num => num > 10); // Outputs: 12

5. findIndex()

The findIndex() method works like find() but returns the index of the first element that satisfies the condition. If no elements match, it returns -1.

Example:

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const numbers = [5, 12, 8, 130, 44];
let index = numbers.findIndex(num => num > 10); // Outputs: 1

6. findLast()

The findLast() method is similar to find(), but it returns the last element in the array that matches the condition. If no elements match, it returns undefined.

Example:

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const numbers = [5, 12, 8, 130, 44];
let lastFound = numbers.findLast(num => num > 10); // Outputs: 44

7. findLastIndex()

The findLastIndex() method is like findIndex(), but it returns the index of the last element that satisfies the condition. If no elements match, it returns -1.

Example:

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const numbers = [5, 12, 8, 130, 44];
let lastIndex = numbers.findLastIndex(num => num > 10); // Outputs: 4

Key Points for Array Search Method

• Basic Value Search: Use indexOf(), lastIndexOf(), or includes() for searching basic values like strings or numbers.
• Complex Conditions: Use find(), findIndex(), findLast(), or findLastIndex() when searching for elements based on conditions or custom criteria.