JavaScript: Remove null, 0, blank, false, undefined and NaN values from an array

Last update on March 03 2025 12:46:16 (UTC/GMT +8 hours)

JavaScript Array: Exercise-24 with Solution

Remove Falsy Values

Write a JavaScript function to remove. 'null', '0', '""', 'false', 'undefined' and 'NaN' values from an array.

Sample array: [NaN, 0, 15, false, -22, '',undefined, 47, null]
Expected result: [15, -22, 47]

Visual Presentation:

JavaScript: Remove null, 0, blank, false, undefined and NaN values from an array

Sample Solution:

JavaScript Code:

// Function to filter an array and remove falsy values
function filter_array(test_array) {
    // Initialize index to -1, arr_length to the length of the array (if not provided, default to 0),
    // resIndex to -1, and result as an empty array
    var index = -1,
        arr_length = test_array ? test_array.length : 0,
        resIndex = -1,
        result = [];

    // Iterate through the elements of the test_array using a while loop
    while (++index < arr_length) {
        // Get the current value from the array
        var value = test_array[index];

        // Check if the value is truthy
        if (value) {
            // If truthy, add it to the result array and increment resIndex
            result[++resIndex] = value;
        }
    }

    // Return the filtered result array
    return result;
}

// Output the result of the filter_array function with a sample array
console.log(filter_array([NaN, 0, 15, false, -22, '', undefined, 47, null]));

Output:

[15,-22,47]

Flowchart:

ES6 Version:

// Function to filter an array and remove falsy values
const filter_array = (test_array) => {
    // Initialize index to -1, arr_length to the length of the array (if not provided, default to 0),
    // resIndex to -1, and result as an empty array
    let index = -1,
        arr_length = test_array ? test_array.length : 0,
        resIndex = -1,
        result = [];

    // Iterate through the elements of the test_array using a while loop
    while (++index < arr_length) {
        // Get the current value from the array
        let value = test_array[index];

        // Check if the value is truthy
        if (value) {
            // If truthy, add it to the result array and increment resIndex
            result[++resIndex] = value;
        }
    }

    // Return the filtered result array
    return result;
};

// Output the result of the filter_array function with a sample array
console.log(filter_array([NaN, 0, 15, false, -22, '', undefined, 47, null]));

Live Demo:

For more Practice: Solve these Related Problems:

Write a JavaScript function that removes false, null, 0, "", undefined, and NaN values from an array using the filter() method.
Write a JavaScript function that iterates over an array and retains only truthy values.
Write a JavaScript function that creates a new array containing only truthy elements from the input array.
Write a JavaScript function that validates the input array and returns a clean array of truthy values.

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