JavaScript Array Methods
Converting Arrays to Strings
The JavaScript method toString() converts an array to a string of (comma separated) array values.Example
var fruits = ["Banana", "Orange", "Apple", "Mango"];
document.getElementById("demo").innerHTML = fruits.toString(); Result
Banana,Orange,Apple,MangoExample
var fruits = ["Banana", "Orange", "Apple", "Mango"];
document.getElementById("demo").innerHTML = fruits.join(" * "); Result
Banana * Orange * Apple * MangoPopping 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 Example
var fruits = ["Banana", "Orange", "Apple", "Mango"];
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
var fruits = ["Banana", "Orange", "Apple", "Mango"];
fruits.push("Kiwi"); // Adds a new element ("Kiwi") to fruits Example
var fruits = ["Banana", "Orange", "Apple", "Mango"];
var x = fruits.push("Kiwi"); // the value of x is 5 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 Example
var fruits = ["Banana", "Orange", "Apple", "Mango"];
fruits.shift(); // Returns "Banana" Example
var fruits = ["Banana", "Orange", "Apple", "Mango"];
fruits.unshift("Lemon"); // Adds a new element "Lemon" to fruits Example
var fruits = ["Banana", "Orange", "Apple", "Mango"];
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
var fruits = ["Banana", "Orange", "Apple", "Mango"];
fruits[0] = "Kiwi"; // Changes the first element of fruits to "Kiwi" Example
var fruits = ["Banana", "Orange", "Apple", "Mango"];
fruits[fruits.length] = "Kiwi"; // Appends "Kiwi" to fruit 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 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"); 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.
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 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 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 Example (Merging an Array with Values)
var arr1 = ["Cecilie", "Lone"];
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 fruits = ["Banana", "Orange", "Lemon", "Apple", "Mango"];
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 fruits = ["Banana", "Orange", "Lemon", "Apple", "Mango"];
var citrus = fruits.slice(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); Example
var fruits = ["Banana", "Orange", "Lemon", "Apple", "Mango"];
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
var fruits = ["Banana", "Orange", "Apple", "Mango"];
document.getElementById("demo").innerHTML = fruits.toString(); Example
var fruits = ["Banana", "Orange", "Apple", "Mango"];
document.getElementById("demo").innerHTML = fruits; All JavaScript objects have a toString() method.
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.
