How to check if array is empty or null or undefined in javascript? — ItSolutionStuff.com

Is there any way to check if there is a null value in an object or array in JavaScript?

Null values can be tricky to work with in JavaScript, but they are an important part of the language. In this article, we will discuss various ways you can check if there is a null value in an object or array in JavaScript.

The null values display that no object value is present. It is intentionally set to show that a variable has been declared but has not yet been given a value.

The primitive value is undefined, which is an unintended absence of any object value, which is comparable to null, that contrasts with the former. This is due to the fact that a declared variable that has not yet been given a value is undefined rather than null. There are many ways to check whether a value is null or not in JavaScript. Let’s discuss few ways one by one.

Using Object.keys()in JavaScript

The Object.keys() is a method in JavaScript that returns an array of the keys of an object. It takes one parameter, which is the object whose keys are to be returned. The order of the keys in the array is based on how they were added to the object; newer properties will appear after older ones. Object.keys can also be used for arrays, since arrays are objects as well and each element in an array has its own key (index).

Syntax

Following is the syntax for the Object.keys() method.

Example

In the following example we are running the script using Object.keys.

When the script is executed, the event is triggered, allowing us to check the entire data set that was used in the script to determine whether the null present is present or not, and it will display null present in the first set of data and actual data in the second set of data right on the webpage based on our data.

Using JavaScript some()method

The some() method accepts a function as a parameter and tests, whether at least one element in the array passes the test implemented by the given function.

It returns true, when an element for which the provided function returns true; otherwise it returns false.

Syntax

Following is the syntax for some() method

array.some(function(value, index, arr), this)

Example

Considering the following example, where we are using the some() method to check whether null is present or not.

On running the above script, the web-browser will display the value «true» on the webpage as the event gets triggered and checks whether the given array consists of null values or not, and it will display «true» as the condition was matched and the given array consists of null values.

Using JavaScript include() Method

The JavaScript include() method is used to load an external script or file into the current document. This method allows you to add scripts, libraries, and other files from outside of the existing HTML page. It can be used with both inline and external scripts. The include() method will execute the code in the specified file before continuing with the rest of your program.

Syntax

Following is the syntax for include()

string.includes(searchvalue, start)

Example

Let’s look into the following example where we are using the include() method

When the script gets executed, the event gets triggered, which checks the data entered in the script to see whether, it contains null value or not and displays the value on the webpage. In the above case, it shows that the array does not contain null value and the object contains null value.

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How To Check Array Is Empty Or Null In Javascript

In this example i will show you how to check array is empty or null in javascript or jquey. When we are working in javascript and you want to loop the array that time we need to check whether array is empty or not. To check if an array is empty or not, you can use the .length property. The length property sets or returns the number of elements in an array. empty array will have 0 elements inside. so, it doesn’t return error.

There are many ways to check javascript array is empty or not. JavaScript provides in-built functions to check whether the array is empty or not.

This method is reliable to check whether array is empty or contains elements.

Many times we required to check that array should not be undefined object and has at least one element. This can be also check with typeof.

We can check array with length, if array length is 0 then array is empty.

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How to Check Array Is Empty Or Null In Javascript?

If need for jquery check if array is empty or undefined then i will help you. you can easily check if array is empty or not in javascript. we will use simple if condition and length of array with checking. so we can easily check if array is empty null undefined in javascript.

Here i will give you simple example with multiple cases so you can use any one from there. i will suggest you that you can use this one as bellow simple code:

if (myArray && myArray.length > 0) console.log(‘myArray is not empty.’);

>else console.log(‘myArray is empty.’);

>

You can also see bellow full example for checking jquery array if empty. So let’s bellow code and also check output as i attached bellow:

/*

Basic Checking for Jquery Array

*/

var myArray = [1, 2, 3];

if (myArray && myArray.length > 0) console.log(‘myArray is not empty.’);

>else console.log(‘myArray is empty.’);

>

/*

Basic Checking with empty array for Jquery Array

*/

var myArray2 = [];

if (myArray2 && myArray2.length > 0) console.log(‘myArray2 is not empty.’);

>else console.log(‘myArray2 is empty.’);

>

/*

Basic Checking with undefined array for Jquery Array

*/

if (typeof myArray3 !== ‘undefined’ && myArray3.length > 0) console.log(‘myArray3 is not empty.’);

>else console.log(‘myArray3 is empty.’);

>

/*

Basic Checking with null array for Jquery Array

*/

var myArray4 = null;

if (myArray4 && myArray4.length > 0) console.log(‘myArray4 is not empty.’);

>else console.log(‘myArray4 is empty.’);

>

myArray is not empty.

myArray2 is empty.

myArray3 is empty.

myArray4 is empty.

Hardik Savani

I’m a full-stack developer, entrepreneur and owner of Aatman Infotech. I live in India and I love to write tutorials and tips that can help to other artisan. I am a big fan of PHP, Laravel, Angular, Vue, Node, Javascript, JQuery, Codeigniter and Bootstrap from the early stage. I believe in Hardworking and Consistency.

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How To Check If All Values In Array Are Null In JavaScript

During JavaScript application development, you will often encounter the request to check if all values in array are null. This article will share how to check if all values in array are null in JavaScript. Let’s get started.

How to check if all values in array are null in JavaScript

The solution in this article to check if all values in an array in JavaScript are null is to use the Array.every() method. First, we will learn about every() method, its syntax, and how to use it.

The every() method is used to check all the elements in the input array using a provided callback function. The every() method will return true if all elements pass the test.

Callback function: A function is called again for each element. This function performs the element test and returns true if the element passes the test.

If the callback function returns a false value, the every() method will stop checking and return false. The every() method returns true if the input array is empty.

To check if all the values in the array are null using every() method, we pass this method a callback function that checks if the array element is null. The following code describes how we do this.

// Check if all elements in the array are null function isNull(array) < return array.every((value) =>value === null); > // Create an array const nullArr = [null, null, null]; console.log(isNull(nullArr)); const numArr = [2, 1, 0, 6, null, 12]; console.log(isNull(numArr));

Another solution is to use every() method in combination with the NOT operator (!). This solution can work for all falsy values.

We will use the NOT operator to convert the values in the array to boolean values. The NOT operator will return true for falsy values. If all values in the array are falsy, the every() method will return true.

// Check if all elements in the array are null function isNull(array) < return array.every((value) =>!value); > // Create an array const nullArr = [null, null, null]; console.log(isNull(nullArr)); const falsyArr = [false, "", 0, null, undefined, NaN]; console.log(isNull(falsyArr)); const numArr = [2, 1, 0, 6, 13, 12]; console.log(isNull(numArr));

Summary

This article shared how to check if all values in an array are null in JavaScript. You can use every() method with the logical NOT operator. Your code will work correctly for other falsy values. Thank you for reading.

Hello, my name’s Bruce Warren. You can call me Bruce. I’m interested in programming languages, so I am here to share my knowledge of programming languages with you, especially knowledge of C, C++, Java, JS, PHP.

Name of the university: KMA
Major: ATTT
Programming Languages: C, C++, Java, JS, PHP

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Check if array is empty or null in Javascript

When working in Javascript, many times you need to check if array is empty or undefined. This needs to check when you want to loop the array, so it doesn’t return error.

There are lot of ways to check if Javascript array is empty or not. Here are some examples:

Checking by array length

The first way to check is to get array length. If the array length is 0, then it empty array.

Checking if array is not undefined

Sometimes you also want to check that array should not be undefined object and has at least one element. This can be also check with typeof.

Using JQuery isEmptyObject() method

We can also use JQuery isEmptyObject method to check whether array is empty or contains elements. This is reliable method.

This way you can check wether array contains element or is empty. I hope this article will help you a little.

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