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The JavaScript method toString() converts an array to a string of (comma separated) array values
The JavaScript method toString()
converts an array to a
string of (comma separated) array values.
const fruits = ["Banana", "Orange", "Apple", "Mango"];
document.getElementById("demo").innerHTML = fruits.toString();
Result:
The join()
method also joins all array elements into a string.
It behaves just like toString()
, but in addition you can specify the separator:
const fruits = ["Banana", "Orange", "Apple", "Mango"];
document.getElementById("demo").innerHTML = fruits.join(" * ");
Result:
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.
The pop()
method removes the last element from an array:
const fruits = ["Banana", "Orange", "Apple", "Mango"];
fruits.pop();
The pop()
method returns the value that was "popped out":
const fruits = ["Banana", "Orange", "Apple", "Mango"];
let fruit = fruits.pop();
The push()
method adds a new element to an array (at the end):
const fruits = ["Banana", "Orange", "Apple", "Mango"];
fruits.push("Kiwi");
The push()
method returns the new array length:
const fruits = ["Banana", "Orange", "Apple", "Mango"];
let length = fruits.push("Kiwi");
Shifting is equivalent to popping, but 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.
const fruits = ["Banana", "Orange", "Apple", "Mango"];
fruits.shift();
The shift()
method returns the value that was "shifted out":
const fruits = ["Banana", "Orange", "Apple", "Mango"];
let fruit = fruits.shift();
The unshift()
method adds a new element to an array (at the beginning), and "unshifts"
older elements:
const fruits = ["Banana", "Orange", "Apple", "Mango"];
fruits.unshift("Lemon");
The unshift()
method returns the new array length.
const fruits = ["Banana", "Orange", "Apple", "Mango"];
fruits.unshift("Lemon");
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 ...
const fruits = ["Banana", "Orange", "Apple", "Mango"];
fruits[0] = "Kiwi";
The length
property provides an easy way to append a new element to an array:
const fruits = ["Banana", "Orange", "Apple", "Mango"];
fruits[fruits.length] = "Kiwi";
Array elements can be deleted using the JavaScript operator delete
.
Using delete
leaves undefined
holes in the
array.
Use pop() or shift() instead.
const fruits = ["Banana", "Orange", "Apple", "Mango"];
delete fruits[0];
The concat()
method creates a new array by merging (concatenating)
existing arrays:
const myGirls = ["Cecilie", "Lone"];
const myBoys = ["Emil", "Tobias", "Linus"];
const myChildren = myGirls.concat(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:
const arr1 = ["Cecilie", "Lone"];
const arr2 = ["Emil", "Tobias", "Linus"];
const arr3 = ["Robin", "Morgan"];
const myChildren = arr1.concat(arr2, arr3);
The concat()
method can also take strings as arguments:
const arr1 = ["Emil", "Tobias", "Linus"];
const myChildren = arr1.concat("Peter");
The splice()
method adds new items to an array.
The slice()
method slices out a piece of an array.
The splice()
method can be used to add new items to an array:
const fruits = ["Banana", "Orange", "Apple", "Mango"];
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.
The rest of the parameters ("Lemon" , "Kiwi") define the new elements to be added.
The splice()
method returns an array with the deleted items:
const fruits = ["Banana", "Orange", "Apple", "Mango"];
fruits.splice(2, 2, "Lemon", "Kiwi");
With clever parameter setting, you can use splice()
to remove elements without leaving
"holes" in the array:
const fruits = ["Banana", "Orange", "Apple", "Mango"];
fruits.splice(0, 1);
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.
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"):
const fruits = ["Banana", "Orange", "Lemon", "Apple", "Mango"];
const citrus = fruits.slice(1);
The slice()
method creates a new array.
The slice()
method does not remove any elements from the source array.
This example slices out a part of an array starting from array element 3 ("Apple"):
const fruits = ["Banana", "Orange", "Lemon", "Apple", "Mango"];
const 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.
const fruits = ["Banana", "Orange", "Lemon", "Apple", "Mango"];
const 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.
const fruits = ["Banana", "Orange", "Lemon", "Apple", "Mango"];
const citrus = fruits.slice(2);
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:
const fruits = ["Banana", "Orange", "Apple", "Mango"];
document.getElementById("demo").innerHTML = fruits.toString();
const fruits = ["Banana", "Orange", "Apple", "Mango"];
document.getElementById("demo").innerHTML = fruits;
All JavaScript objects have a toString() method.
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 are covered in the next chapter of this tutorial.
For a complete Array reference, go to our:
Complete JavaScript Array Reference.
The reference contains descriptions and examples of all Array properties and methods.
Use the correct Array method to remove the last item of the fruits
array.
const fruits = ["Banana", "Orange", "Apple"]; ;