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

Last update on May 30 2022 10:07:27 (UTC/GMT +8 hours)

JavaScript Array: Exercise-24 with Solution

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]

Pictorial Presentation:

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

Sample Solution:

HTML Code:

<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>Write a JavaScript function to remove. 'null', '0', '""', 'false', 'undefined' and 'NaN' values from an array.</title>
</head>
<body>
</body>
</html>

JavaScript Code:

function filter_array(test_array) {
    var index = -1,
        arr_length = test_array ? test_array.length : 0,
        resIndex = -1,
        result = [];

    while (++index < arr_length) {
        var value = test_array[index];

        if (value) {
            result[++resIndex] = value;
        }
    }

    return result;
}
console.log(filter_array([NaN, 0, 15, false, -22, '',undefined, 47, null]));

Sample Output:

[15,-22,47]

Flowchart:

ES6 Version:

function filter_array(test_array) {
    let index = -1;
    const arr_length = test_array ? test_array.length : 0;
    let resIndex = -1;
    const result = [];

    while (++index < arr_length) {
        const value = test_array[index];

        if (value) {
            result[++resIndex] = value;
        }
    }

    return result;
}
console.log(filter_array([NaN, 0, 15, false, -22, '',undefined, 47, null]));

Live Demo:

See the Pen JavaScript - Remove null, 0, blank, false, undefined and NaN values from an array - array-ex- 24 by w3resource (@w3resource) on CodePen.

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Next: Write a JavaScript function to sort the following array of objects by title value.

JavaScript: Tips of the Day

How to insert an item into an array at a specific index (JavaScript)?

What you want is the splice function on the native array object.

arr.splice(index, 0, item); will insert item into arr at the specified index (deleting 0 items first, that is, it's just an insert). In this example we will create an array and add an element to it into index 2:

var arr = []; arr[0] = "Jani"; arr[1] = "Hege"; arr[2] = "Stale"; arr[3] = "Kai Jim"; arr[4] = "Borge"; console.log(arr.join()); arr.splice(2, 0, "Lene"); console.log(arr.join());

Ref: https://bit.ly/2BXbp04