10 Genius Hacks Using Array.filter() That You Must Try

Array filtering in JavaScript is a powerful feature that can be used creatively and practically.

Here are some innovative uses of the array.filter method:

1. Removing Duplicates

const numbers = [1, 2, 2, 3, 4, 4, 5];

const uniqueNumbers = numbers.filter((value, index, self) => self.indexOf(value) === index);

// uniqueNumbers: [1, 2, 3, 4, 5]

2. Finding Prime Numbers

const numbers = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10];

const isPrime = num => {

for (let i = 2, s = Math.sqrt(num); i <= s; i++)

if (num % i === 0) return false;

return num > 1;

};

const primeNumbers = numbers.filter(isPrime);

// primeNumbers: [2, 3, 5, 7]

3. Filtering Objects by Property

const users = [

{ name: ‘Alice‘, age: 25 },

{ name: ‘Bob‘, age: 30 },

{ name: ‘Charlie‘, age: 25 }

];

const age25 = users.filter(user => user.age === 25);

// age25: [{ name: ‘Alice’, age: 25 }, { name: ‘Charlie’, age: 25 }]

4. Excluding Falsy Values

const values = [0, 1, false, 2, ”, 3, null, undefined, 4];

const truthyValues = values.filter(Boolean);

// truthyValues: [1, 2, 3, 4]

5. Filtering Nested Arrays

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

const flattenedAndFiltered = nestedArrays.flat().filter(num => num > 5);

// flattenedAndFiltered: [6, 7, 8, 9]

6. Filtering Unique Values in Nested Arrays

const arrays = [[1, 2, 3], [3, 4, 5], [5, 6, 7]];

const uniqueValues = […new Set(arrays.flat())];

// uniqueValues: [1, 2, 3, 4, 5, 6, 7]

7. Filtering by Date Range

const events = [

{ name: ‘Event 1‘, date: new Date(‘2023-01-01‘) },

{ name: ‘Event 2‘, date: new Date(‘2023-06-01‘) },

{ name: ‘Event 3‘, date: new Date(‘2023-12-01‘) }

];

const startDate = new Date(‘2023-01-01‘);

const endDate = new Date(‘2023-06-30‘);

const filteredEvents = events.filter(event => event.date >= startDate && event.date <= endDate);

// filteredEvents: [{ name: ‘Event 1’, date: new Date(‘2023-01-01’) }, { name: ‘Event 2’, date: new Date(‘2023-06-01’) }]

8. Filtering with Multiple Conditions

const products = [

{ name: ‘Laptop‘, price: 1000, inStock: true },

{ name: ‘Phone‘, price: 500, inStock: false },

{ name: ‘Tablet‘, price: 300, inStock: true }

];

const availableExpensiveProducts = products.filter(product => product.inStock && product.price > 400);

// availableExpensiveProducts: [{ name: ‘Laptop’, price: 1000, inStock: true }]

9. Filtering Array of Strings by Length

const words = [‘apple‘, ‘banana‘, ‘cherry‘, ‘date‘];

const longWords = words.filter(word => word.length > 5);

// longWords: [‘banana’, ‘cherry’]

10. Filtering Non-Numeric Values

const mixedValues = [1, ‘two‘, 3, ‘four‘, 5];

const numericValues = mixedValues.filter(value => typeof value === ‘number‘);

// numericValues: [1, 3, 5]

Thank you for reading!

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