JAVASCRIPT

how the filter() function works javascript

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

const filter = arr.filter((number) => number > 5);
console.log(filter); // [6, 7, 8, 9]

How does filter works in javascript?

const products = [
    { name: 'Laptop', price: 32000, brand: 'Lenovo', color: 'Silver' },
    { name: 'Phone', price: 700, brand: 'Iphone', color: 'Golden' },
    { name: 'Watch', price: 3000, brand: 'Casio', color: 'Yellow' },
    { name: 'Aunglass', price: 300, brand: 'Ribon', color: 'Blue' },
    { name: 'Camera', price: 9000, brand: 'Lenovo', color: 'Gray' },
];
//Get products that price is greater than 3000 by using a filter
const getProduct = products.filter(product => product.price > 3000);
console.log(getProduct)
//Expected output:
/*[
    { name: 'Laptop', price: 32000, brand: 'Lenovo', color: 'Silver' },
    { name: 'Camera', price: 9000, brand: 'Lenovo', color: 'Gray' }
  ]
*/

how to create my own filter in js

// filter takes an array and function as argumentfunction 
filter(arr, filterFunc) {
  const filterArr = []; // empty array        
  // loop though array    
  for(let i=0;i<arr.length;i++) {        
    const result = filterFunc(arr[i], i, arr);        
    // push the current element if result is true        
    if(result)             
      filterArr.push(arr[i]);     
  }    
  return filterArr;
}