Check if an array is empty or not in JavaScript
For doing any operation on the array it is important to have elements in an array. we can check the presence of elements in an array by calculating the length of that array, also there are many other ways to check whether the array is empty or not.
These are the following methods to Check if an Array is Empty or Not:
Table of Content
- Method 1: Using array.isArray() method and array.length property
- Method 2: Checking the type and length of the array
- Method 3: Using JavaScript Array.some() method
- Method 4: Using JavaScript toSrting() method
- Method 5: Using JavaScript Array.every()
- Method 6: Using JSON.stringify():
- Using JavaScript Array.prototype.findIndex Method
Method 1: Using array.isArray() method and array.length property
- Check array existence and type with
Array.isArray(). - Verify emptiness using
array.length. - Combine both with
&&to ensure the array exists and is not empty.
Syntax:
Array.isArray(emptyArray) && emptyArray.length
Example: This example shows the above-explained approach.
function checkArray() {
// Input arrays
let emptyArray = [];
let nonExistantArray = undefined;
let fineArray = [1, 2, 3, 4, 5];
// Checking for type and array length
if (Array.isArray(emptyArray) && emptyArray.length)
output = true;
else output = false;
// Display output
console.log("Output for emptyArray:" + output);
// Checking for type and array length
if (
Array.isArray(nonExistantArray) &&
nonExistantArray.length
)
output = true;
else output = false;
// Display output
console.log("Output for nonExistantArray:" + output);
// Checking for type and array length
if (Array.isArray(fineArray) && fineArray.length)
output = true;
else output = false;
// Display output
console.log("Output for fineArray:" + output);
}
// Function call
checkArray();
Output
Output for emptyArray:false Output for nonExistantArray:false Output for fineArray:true
Method 2: Checking the type and length of the array
- Verify array existence by checking for ‘undefined’ or ‘null’ using the
typeofoperator. - Check if the array is empty by ensuring the existence of the
array.lengthproperty and confirming it’s greater than 0. - Use the AND (
&&) operator to ensure both array existence and non-emptiness.
Syntax:
typeof emptyArray != "undefined" && emptyArray != null && emptyArray.length != null
&& emptyArray.length > 0
Example: This example shows the use of the above-explained approach.
function checkArray() {
// Array inputs
let emptyArray = [];
let nonExistantArray = undefined;
let fineArray = [1, 2, 3, 4, 5];
// Checking array type and length
if (
typeof emptyArray != "undefined" &&
emptyArray != null &&
emptyArray.length != null &&
emptyArray.length > 0
)
output = true;
else output = false;
// Display output
console.log("Output for emptyArray:" + output);
// Checking array type and length
if (
typeof nonExistantArray != "undefined" &&
nonExistantArray != null &&
nonExistantArray.length != null &&
nonExistantArray.length > 0
)
output = true;
else output = false;
// Display output
console.log("Output for nonExistantArray:" + output);
// Checking array type and length
if (
typeof fineArray != "undefined" &&
fineArray != null &&
fineArray.length != null &&
fineArray.length > 0
)
output = true;
else output = false;
// Display output
console.log("Output for fineArray:" + output);
}
checkArray();
Output
Output for emptyArray:false Output for nonExistantArray:false Output for fineArray:true
Method 3: Using JavaScript Array.some() method
The Javascript arr.some() method checks whether at least one of the elements of the array satisfies the condition checked by the argument method.
Syntax:
arr.some(callback(element,index,array),thisArg)
Example: In this example, we will use JavaScript Array.some() method to check an empty array.
function checkArray() {
// Array inputs
let emptyArray = [];
let fineArray = [1, 2, 3, 4, 5];
// Checking array
let output = emptyArray.some((element) => true);
// Display output
console.log("Output for emptyArray:" + output);
// Checking array
output = fineArray.some((element) => true);
// Display output
console.log("Output for fineArray:" + output);
}
// Function call
checkArray();
Output
Output for emptyArray:false Output for fineArray:true
Method 4: Using JavaScript toSrting() method
The JavaScript Array toString() Method returns the string representation of the array elements
Syntax:
arr.toString()
Example: In this article, we will use JavaScript toString() mehod to convert the given array to string and compare it with an empty string to give output.
function checkArray() {
// Array inputs
let emptyArray = [];
let fineArray = [1, 2, 3, 4, 5];
// Checking array
let output = emptyArray.toString() === "";
// Display output
console.log("Output for emptyArray:" + !output);
// Checking array
output = fineArray.toString() === "";
// Display output
console.log("Output for fineArray:" + !output);
}
// Function call
checkArray();
Output
Output for emptyArray:false Output for fineArray:true
Method 5: Using JavaScript Array.every()
The JavaScript Array.every() method tests whether all elements in the array pass the test implemented by the provided function. This method returns true if the callback function returns true for every element in the array; otherwise, it returns false.
Syntax:
arr.every(callback(element, index, array), thisArg)
Example: In this example, we’ll use the Array.every() method to check if the array is empty.
function checkArray() {
// Array inputs
let emptyArray = [];
let fineArray = [1, 2, 3, 4, 5];
// Checking array
let output = emptyArray.every((element) => false);
// Display output
console.log("Output for emptyArray:" + !output);
// Checking array
output = fineArray.every((element) => false);
// Display output
console.log("Output for fineArray:" + !output);
}
// Function call
checkArray();
Output
Output for emptyArray:false Output for fineArray:true
Method 6: Using JSON.stringify():
Using JSON.stringify() to check if an array is empty involves converting the array to a JSON string and comparing it to ‘[]’. While it works, it’s inefficient and less readable compared to using `array.length === 0`.
Example: In this example The function isArrayEmpty uses array.length === 0 to check if an array is empty. It is efficient and readable. It correctly identifies emptyArray as empty and `nonEmptyArray` as not empty.
function isArrayEmpty(array) {
return array.length === 0;
}
const emptyArray = [];
const nonEmptyArray = [1, 2, 3];
console.log("Is emptyArray empty?", isArrayEmpty(emptyArray));
console.log("Is nonEmptyArray empty?", isArrayEmpty(nonEmptyArray));
Output
Is emptyArray empty? true Is nonEmptyArray empty? false
Using JavaScript Array.prototype.findIndex Method
Another approach to check if an array is empty or not in JavaScript is by using the findIndex method. This method returns the index of the first element in the array that satisfies the provided testing function. If no elements satisfy the testing function, it returns -1. By checking the returned index, we can determine if the array is empty.
Example: In this example, we will use the findIndex method to check if an array is empty.
function isArrayEmpty(array) {
// If findIndex returns -1, the array is empty
return array.findIndex(() => true) === -1;
}
// Array inputs
const emptyArray = [];
const nonEmptyArray = [1, 2, 3, 4, 5];
// Checking array
console.log("Is emptyArray empty?", isArrayEmpty(emptyArray)); // Output: true
console.log("Is nonEmptyArray empty?", isArrayEmpty(nonEmptyArray)); // Output: false
Output
Is emptyArray empty? true Is nonEmptyArray empty? false
JavaScript is best known for web page development but it is also used in a variety of non-browser environments. You can learn JavaScript from the ground up by following this JavaScript Tutorial and JavaScript Examples.
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