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
document.getElementById('demo').innerHTML = fruits.toString();
Result:
Try it Yourself »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
document.getElementById('demo').innerHTML = fruits.join(' * ');
Result:
Try it Yourself »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
fruits.pop(); // Removes the last element ('Mango') from fruits
The pop()
method returns the value that was 'popped out':
Example
var x = fruits.pop(); // the value of x is 'Mango'
Pushing
The push()
method adds a new element to an array (at the end):
Example
fruits.push('Kiwi'); // Adds a new element ('Kiwi') to fruits
The push()
method returns the new array length:
Example
var x = fruits.push('Kiwi'); // the value of x is 5
Javascript Remove Empty Array Values
Try it Yourself »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
fruits.shift(); // Removes the first element 'Banana' from fruits
The shift()
method returns the string that was 'shifted out':
Example
var x = fruits.shift(); // the value of x is 'Banana'
The unshift()
method adds a new element to an array (at the beginning), and 'unshifts' older elements:
Example
fruits.unshift('Lemon'); // Adds a new element 'Lemon' to fruits
The unshift()
method returns the new array length.
Example
fruits.unshift('Lemon'); // Returns 5
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
fruits[0] = 'Kiwi'; // Changes the first element of fruits to 'Kiwi'
The length
property provides an easy way to append a new element to an array:
Example
fruits[fruits.length] = 'Kiwi'; // Appends 'Kiwi' to fruits
Deleting Elements
Since JavaScript arrays are objects, elements can be deleted by using the JavaScript operator delete
:
Example
delete fruits[0]; // Changes the first element in fruits to undefined
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
fruits.splice(2, 0, 'Lemon', 'Kiwi');
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
fruits.splice(2, 2, 'Lemon', 'Kiwi');
Using splice() to Remove Elements
With clever parameter setting, you can use splice()
to remove elements without leaving 'holes' in the array:
Example
fruits.splice(0, 1); // Removes the first element of fruits
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 myBoys = ['Emil', 'Tobias', 'Linus'];
var myChildren = myGirls.concat(myBoys); // Concatenates (joins) myGirls and myBoys
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 arr2 = ['Emil', 'Tobias', 'Linus'];
var arr3 = ['Robin', 'Morgan'];
var myChildren = arr1.concat(arr2, arr3); // Concatenates arr1 with arr2 and arr3
The concat()
method can also take values as arguments:
Example (Merging an Array with Values)
var myChildren = arr1.concat(['Emil', 'Tobias', 'Linus']);
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 citrus = fruits.slice(1);
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 citrus = fruits.slice(3);
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 citrus = fruits.slice(1, 3);
If the end argument is omitted, like in the first examples, the slice()
method slices out the rest of the array.
Example
var citrus = fruits.slice(2);
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
document.getElementById('demo').innerHTML = fruits.toString();
Example
document.getElementById('demo').innerHTML = fruits;
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.