JavaScript array has more than one value at a time. In another word you can say an Array is a collection of similar types of elements.
Note: Array index is starts 0.
Syntax
Declaring an Array
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let arr = new Array(); let arr = []; |
Creating an Array
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var array_name = [item1, item2, ...]; |
Example JavaScript Array
Creating Array with values.
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<html> <head> <title>Sample Code</title> <script type="text/javascript"> var num = [1, 2, 3, 4, 5 ]; alert(num) </script> </head> </html> |
Output:

Using the JavaScript Keyword new
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<html> <head> <title>Sample Code</title> <script type="text/javascript"> var num = new Array(); num[0] = "a"; num[1] = "b"; alert(num) </script> </head> </html> |
Output: a,b
Advantage of Array
- JS Arrays represent multiple data items of the same type using a single name.
- In arrays, the elements can be accessed randomly by using the index number.
List of JavaScript array methods
Arrays provide a lot of methods. A cheat sheet of array methods in JavaScript:
- To add/remove elements:
push(...items)
– adds items to the end,pop()
– extracts an item from the end,shift()
– extracts an item from the beginning,unshift(...items)
– adds items to the beginning.splice(pos, deleteCount, ...items)
– at indexpos
deletedeleteCount
elements and insertitems
.slice(start, end)
– creates a new array, copies elements from positionstart
tillend
(not inclusive) into it.concat(...items)
– returns a new array: copies all members of the current one and addsitems
to it. If any ofitems
is an array, then its elements are taken.
- To search among elements:
indexOf/lastIndexOf(item, pos)
– look foritem
starting from positionpos
, return the index or-1
if not found.includes(value)
– returnstrue
if the array hasvalue
, otherwisefalse
.find/filter(func)
– filter elements through the function, return first/all values that make it returntrue
.findIndex
is likefind
, but returns the index instead of a value.
- To iterate over elements:
forEach(func)
– callsfunc
for every element, does not return anything.
- To transform the array:
map(func)
– creates a new array from results of callingfunc
for every element.sort(func)
– sorts the array in-place, then returns it.reverse()
– reverses the array in-place, then returns it.split/join
– convert a string to array and back.reduce(func, initial)
– calculate a single value over the array by callingfunc
for each element and passing an intermediate result between the calls.
- Additionally:
Array.isArray(arr)
checksarr
for being an array.
Q: How to get the JavaScript array length?
Answer: Using the length property you can get the length of an array (the number of array elements).
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<html> <head> <title>Sample Code</title> <script type="text/javascript"> var fruits = ["Banana", "Orange", "Apple", "Mango"]; alert(fruits.length); </script> </head> </html> |
Output: 4
Do comment if you have any doubts and suggestion on this topic.
Note: All JS Examples codes are tested on the Firefox browser and the Chrome browser.
OS: Windows 10
Code: HTML 5 Version