Javascript Array Remove Empty Slots

Converting Arrays to Strings

The JavaScript method toString() converts an array to a string of (comma separated) array values.

In JavaScript, arrays can be declared literally or they can be initialized using the Array constructor function. But wait What if you want to empty an array instead of creating one? Hmm perhaps not as straightforward. Have no fear, there are some relatively easy ways to go about emptying an array in JavaScript. Removing Elements from JavaScript Arrays July 16, 2016. The JavaScript standard library is notoriously small. In fact, it is so small that the Array prototype doesn't even define a method for removing a specific element from an array. Because there's no such built-in method, developers have to create their own version if they want to remove a specific array element. Remove empty elements from an array in javascript - In some situations we may want to keep 0 in the array and remove anything else null, undefined and, this is one way Toggle sidebar TUTORIALS.

Example

var fruits = ['Banana', 'Orange', 'Apple', 'Mango'];
document.getElementById('demo').innerHTML = fruits.toString();

Result:

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The join() method also joins all array elements into a string.

It behaves just like toString(), but in addition you can specify the separator:

Example

var fruits = ['Banana', 'Orange', 'Apple', 'Mango'];
document.getElementById('demo').innerHTML = fruits.join(' * ');

Result:

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Popping and Pushing

When you work with arrays, it is easy to remove elements and add new elements.

This is what popping and pushing is:

Popping items out of an array, or pushing items into an array.

Popping

The pop() method removes the last element from an array:

Example

var fruits = ['Banana', 'Orange', 'Apple', 'Mango'];
fruits.pop(); // Removes the last element ('Mango') from fruits
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The pop() method returns the value that was 'popped out':

Example

var fruits = ['Banana', 'Orange', 'Apple', 'Mango'];
var x = fruits.pop(); // the value of x is 'Mango'
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Pushing

The push() method adds a new element to an array (at the end):

Example

var fruits = ['Banana', 'Orange', 'Apple', 'Mango'];
fruits.push('Kiwi'); // Adds a new element ('Kiwi') to fruits
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The push() method returns the new array length:

Example

var fruits = ['Banana', 'Orange', 'Apple', 'Mango'];
var x = fruits.push('Kiwi'); // the value of x is 5

Javascript Remove Empty Array Values

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Shifting Elements

Shifting is equivalent to popping, working on the first element instead of the last.

The shift() method removes the first array element and 'shifts' all other elements to a lower index.

Example

var fruits = ['Banana', 'Orange', 'Apple', 'Mango'];
fruits.shift(); // Removes the first element 'Banana' from fruits
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The shift() method returns the string that was 'shifted out':

Example

var fruits = ['Banana', 'Orange', 'Apple', 'Mango'];
var x = fruits.shift(); // the value of x is 'Banana'
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The unshift() method adds a new element to an array (at the beginning), and 'unshifts' older elements:

Example

var fruits = ['Banana', 'Orange', 'Apple', 'Mango'];
fruits.unshift('Lemon'); // Adds a new element 'Lemon' to fruits
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The unshift() method returns the new array length.

Example

var fruits = ['Banana', 'Orange', 'Apple', 'Mango'];
fruits.unshift('Lemon'); // Returns 5
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Changing Elements

Array elements are accessed using their index number:

Array indexes start with 0. [0] is the first array element, [1] is the second, [2] is the third ...

Example

var fruits = ['Banana', 'Orange', 'Apple', 'Mango'];
fruits[0] = 'Kiwi'; // Changes the first element of fruits to 'Kiwi'
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The length property provides an easy way to append a new element to an array:

Example

var fruits = ['Banana', 'Orange', 'Apple', 'Mango'];
fruits[fruits.length] = 'Kiwi'; // Appends 'Kiwi' to fruits
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Deleting Elements

Since JavaScript arrays are objects, elements can be deleted by using the JavaScript operator delete:

Example

var fruits = ['Banana', 'Orange', 'Apple', 'Mango'];
delete fruits[0]; // Changes the first element in fruits to undefined
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Using delete may leave undefined holes in the array. Use pop() or shift() instead.

Splicing an Array

The splice() method can be used to add new items to an array:

Example

var fruits = ['Banana', 'Orange', 'Apple', 'Mango'];
fruits.splice(2, 0, 'Lemon', 'Kiwi');
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The first parameter (2) defines the position where new elements should be added (spliced in).

The second parameter (0) defines how many elements should be removed.

Javascript Remove Null From Array

The rest of the parameters ('Lemon' , 'Kiwi') define the new elements to be added.

The splice() method returns an array with the deleted items:

Example

Javascript remove null from array
var fruits = ['Banana', 'Orange', 'Apple', 'Mango'];
fruits.splice(2, 2, 'Lemon', 'Kiwi');
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Using splice() to Remove Elements

With clever parameter setting, you can use splice() to remove elements without leaving 'holes' in the array:

Example

var fruits = ['Banana', 'Orange', 'Apple', 'Mango'];
fruits.splice(0, 1); // Removes the first element of fruits
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The first parameter (0) defines the position where new elements should be added (spliced in).

The second parameter (1) defines how many elements should be removed.

The rest of the parameters are omitted. No new elements will be added.

Merging (Concatenating) Arrays

The concat() method creates a new array by merging (concatenating) existing arrays:

Example (Merging Two Arrays)

var myGirls = ['Cecilie', 'Lone'];
var myBoys = ['Emil', 'Tobias', 'Linus'];
var myChildren = myGirls.concat(myBoys); // Concatenates (joins) myGirls and myBoys
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The concat() method does not change the existing arrays. It always returns a new array.

The concat() method can take any number of array arguments:

Example (Merging Three Arrays)

var arr1 = ['Cecilie', 'Lone'];
var arr2 = ['Emil', 'Tobias', 'Linus'];
var arr3 = ['Robin', 'Morgan'];
var myChildren = arr1.concat(arr2, arr3); // Concatenates arr1 with arr2 and arr3
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The concat() method can also take values as arguments:

Example (Merging an Array with Values)

Array
var arr1 = ['Cecilie', 'Lone'];
var myChildren = arr1.concat(['Emil', 'Tobias', 'Linus']);
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Slicing an Array

The slice() method slices out a piece of an array into a new array.

This example slices out a part of an array starting from array element 1 ('Orange'):

Example

var fruits = ['Banana', 'Orange', 'Lemon', 'Apple', 'Mango'];
var citrus = fruits.slice(1);
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The slice() method creates a new array. It does not remove any elements from the source array.

This example slices out a part of an array starting from array element 3 ('Apple'):

Example

var fruits = ['Banana', 'Orange', 'Lemon', 'Apple', 'Mango'];
var citrus = fruits.slice(3);
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The slice() method can take two arguments like slice(1, 3).

The method then selects elements from the start argument, and up to (but not including) the end argument.

Example

var fruits = ['Banana', 'Orange', 'Lemon', 'Apple', 'Mango'];
var citrus = fruits.slice(1, 3);
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If the end argument is omitted, like in the first examples, the slice() method slices out the rest of the array.

Example

var fruits = ['Banana', 'Orange', 'Lemon', 'Apple', 'Mango'];
var citrus = fruits.slice(2);
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Automatic toString()

JavaScript automatically converts an array to a comma separated string when a primitive value is expected.

This is always the case when you try to output an array.

These two examples will produce the same result:

Example

var fruits = ['Banana', 'Orange', 'Apple', 'Mango'];
document.getElementById('demo').innerHTML = fruits.toString();
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Example

var fruits = ['Banana', 'Orange', 'Apple', 'Mango'];
document.getElementById('demo').innerHTML = fruits;
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Finding Max and Min Values in an Array

There are no built-in functions for finding the highest or lowest value in a JavaScript array.

You will learn how you solve this problem in the next chapter of this tutorial.

Sorting Arrays

Sorting arrays are covered in the next chapter of this tutorial.

Complete Array Reference

For a complete reference, go to our Complete JavaScript Array Reference.

The reference contains descriptions and examples of all Array properties and methods.