Excluding numerical values from an array using JavaScript

Question

Excluding numerical values from an array using JavaScript

I have been working on a code snippet to filter out numeric values from an array, but instead of getting only the numbers, I am receiving the complete array. I am unable to identify where the issue lies in my code. Can someone please assist me as I am currently stuck and need help with this...

<!doctype html>
<html lang="en">
    <head>
  <meta charset="utf-8">
  <title>HTML Demo</title>
</head>
<body>
<script>
    arr = ["apple", 5, "Mango", 6];
    function filterNumeric(arrayName){
        var i = 0;
        var numericArray=[];
        for (i; i <arrayName.length;i++){
            if (typeof(arrayName[i] === 'number')) {
                numericArray+=arrayName[i];
            }
        }
        return numericArray;
    }

    var filter = filterNumeric(arr);
    alert(filter);
</script>

</body>
</html>

javascript

Answer 1

Answer №1

An error was found in the typeof validation:

if (typeof(arrayName[i]) === 'number') {
//                    ^^^ end parenthesis is here
//                                 ^^^ should not be there

Answer 2

An error was found in the typeof validation:

if (typeof(arrayName[i]) === 'number') {
//                    ^^^ end parenthesis is here
//                                 ^^^ should not be there

Answer 3

Answer №2

When working with JavaScript arrays, you can take advantage of the built-in filter method:

var arr = ["apple", 5, "Mango", 6];
var filtered = arr.filter(function(item) { return (typeof item === "number")});
console.log(filtered); // Array [5,6]

In regard to the original code provided, it's important to note that typeof is an operator and not a function. Therefore,

if (typeof(foo === "whatever")) {
    // ...
}

is essentially equivalent to

if (typeof some_boolean_value) {
    // ...
}

This evaluation resolves to

if ("boolean") {
    // ...
}

resulting in a true statement, causing the entire content to be returned without any filtering.

Furthermore, keep in mind that the += operator is not designed for use with arrays; instead, it will concatenate values as strings:

var foo = [];
var bar = [1,2,3,4];
foo += bar[2];
console.log(foo); // "3"
console.log(typeof foo); // "string"

To properly add elements to an array, utilize the push method:

var foo = [];
var bar = [1,2,3,4];
foo.push(bar[2]);
console.log(foo); // Array [3]
console.log(typeof foo); // "object"

Answer 4

When working with JavaScript arrays, you can take advantage of the built-in filter method:

var arr = ["apple", 5, "Mango", 6];
var filtered = arr.filter(function(item) { return (typeof item === "number")});
console.log(filtered); // Array [5,6]

In regard to the original code provided, it's important to note that typeof is an operator and not a function. Therefore,

if (typeof(foo === "whatever")) {
    // ...
}

is essentially equivalent to

if (typeof some_boolean_value) {
    // ...
}

This evaluation resolves to

if ("boolean") {
    // ...
}

resulting in a true statement, causing the entire content to be returned without any filtering.

Furthermore, keep in mind that the += operator is not designed for use with arrays; instead, it will concatenate values as strings:

var foo = [];
var bar = [1,2,3,4];
foo += bar[2];
console.log(foo); // "3"
console.log(typeof foo); // "string"

To properly add elements to an array, utilize the push method:

var foo = [];
var bar = [1,2,3,4];
foo.push(bar[2]);
console.log(foo); // Array [3]
console.log(typeof foo); // "object"

Excluding numerical values from an array using JavaScript

Answer №1

Answer №2

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