JavaScript Code

JavaScript Array filter()


filter() – filters elements that pass a test

array.filter( function, thisValue )
  • array is the given array
  • every is inbuilt array method name
  • function a function to run for every element. the definition of the function is function(element, index, arr). the function must return a boolean value of true or false
    • element is the current element in the array
    • index of the current element [optional argument]
    • arr is the array of current element [optional argument]
  • this is a value passed to the function as its this value [optional argument]

filter() method creates and returns a new array with the elements from the original array that return true for the given function

Examples

1. filter even numbers from the given numeric array nums

function isEven(num) {
    if (num % 2 == 0) {
        return true;
    } else {
        return false;
    }
}

nums = [4, 1, 8, 0, 2, 3, 5];
evenNumbers = nums.filter(isEven);
console.log(evenNumbers);

2. filter non-empty strings from the given string array names

function isNonEmptyString(item) {
    if (item.length !== 0) {
        return true;
    } else {
        return false;
    }
}

names = ["apple", "banana", "", "cherry", "", "mango"];
nonEmptyNames = names.filter(isNonEmptyString);
console.log(nonEmptyNames);

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