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JavaScript Array Manipulation Tutorial with Examples
The JavaScript Array class is a global object that is used in the construction of arrays; which are high-level, list-like objects.
Description
Arrays are list-like objects whose prototype has methods to perform traversal and mutation operations. Neither the length of a JavaScript array nor the types of its elements are fixed. Since an array’s length can change at any time, and data can be stored at non-contiguous locations in the array, JavaScript arrays are not guaranteed to be dense; this depends on how the programmer chooses to use them. In general, these are convenient characteristics; but if these features are not desirable for your particular use, you might consider using typed arrays.
What is an array in programming? The array is a data type consisting of a collection of elements (value or variable), and each element has an index. Simply, the array is a variable that more powerful. Why? because arrays can hold more than one value. The array can contain string, integer, boolean, and function in one variable.
see the following syntax:
var myArray = ['string', 2, false, myFunction];
or
var myArray = [];
myArray = ['string', 2, false, myFunction];
We can have an array in the array. It’s called the multidimensional array. Here’s the syntaxis:
var myArray = ['string', 2, false, myFunction, [1,2,3]];
Creating an Array
We have several ways to create an array in javascript. The same as an example before, we can directly give a value or variable into an array. Here’s the first way to create an array in javascript.
Example:
var myArray = ['a', 2, true];
we can use the console to see the result:
console.log(myArray);
here’s the full code:
<!DOCTYPE html>
<html lang="en">
<head>
<title>Javascript Array</title>
</head>
<body>
<script>
var myArray = ['a', 2, true];
console.log(myArray);
</script>
</body>
</html>
here’s the result:
But the console displays this as an object in javascript.
The number shown is as an index (index 0 - 2). The index is referring to the value that we have. The index always starts at 0 (zero).
If we want to the console only displaying one value, we can use the index to do it.
Example:
<!DOCTYPE html>
<html lang="en">
<head>
<title>Javascript Array</title>
</head>
<body>
<script>
var myArray = ['a', 2, true];
console.log(myArray[3]);
</script>
</body>
</html>
result:
This is a second way to create an array.
Example:
<!DOCTYPE html>
<html lang="en">
<head>
<title>Javascript Array</title>
</head>
<body>
<script>
var myArray = [];
myArray[0] = ['index 0'];
myArray[1] = ['index 1'];
myArray[2] = ['index 2'];
console.log(myArray);
</script>
</body>
</html>
result:
Important to note, if we want to use this way, the index must be sequential. If it not sequent, the value will become undefined or empty.
Example:
<!DOCTYPE html>
<html lang="en">
<head>
<title>Javascript Array</title>
</head>
<body>
<script>
var myArray = [];
myArray[0] = ['index 0'];
myArray[1] = ['index 1'];
myArray[2] = ['index 2'];
myArray[5] = ['index 5'];
console.log(myArray);
</script>
</body>
</html>
result:
Removing Array Items
If we want to remove an item of the array in javascript, the index is needed.
Note: This is not the right way. I’ll show you in the next example.
Example:
<!DOCTYPE html>
<html lang="en">
<head>
<title>Javascript Array</title>
</head>
<body>
<script>
var myArray = ['a', 2, true];
myArray[1] = undefined;
console.log(myArray);
</script>
</body>
</html>
result:
Displaying Array
We’ll try to display the array in the right way. First, we’ll use javascript looping and display the element of the array by one.
Example:
<!DOCTYPE html>
<html lang="en">
<head>
<title>Javascript Array</title>
</head>
<body>
<script>
var myArray = ['index 0', 'index 1', 'index 2'];
for (var i = 0; i < myArray.length; i++) {
console.log(myArray[i]);
}
</script>
</body>
</html>
Now the array is shown in the right way. Not shown as an object like the example before:
The Method in Javascript Array
You can use a method in the array. The javascript has some methods that can be used in an array.
First, we’ll try to use the “join” method to join all the elements of an array, to make it as a string.
Example:
<!DOCTYPE html>
<html lang="en">
<head>
<title>Javascript Array</title>
</head>
<body>
<script>
var arr = ['Tea', 'Coffee', 'Milk'];
console.log(arr.join());
</script>
</body>
</html>
result:
You can change the separators of the string if you don’t want to use the commas (“,”):
<!DOCTYPE html>
<html lang="en">
<head>
<title>Javascript Array</title>
</head>
<body>
<script>
var arr = ['Tea', 'Coffee', 'Milk'];
console.log(arr.join(' - '));
</script>
</body>
</html>
result:
That’s the example of the “join” method. Now, let’s try the “push” & “pop” method. The “push” method is used to append an element that will be placed in the last of an array. To use it, we can use the simple way.
Example:
<!DOCTYPE html>
<html lang="en">
<head>
<title>Javascript Array</title>
</head>
<body>
<script>
var arr = ['Tea', 'Coffee', 'Milk'];
arr.push('Boba');
console.log(arr.join(' - '));
</script>
</body>
</html>
result:
With the “push” method, you can append some elements like this:
arr.push('Boba', 'Yogurt', 'Lemon');
The “pop” method is the opposite of the “push” method. The “pop” will remove the last element from an array.
Example:
<!DOCTYPE html>
<html lang="en">
<head>
<title>Javascript Array</title>
</head>
<body>
<script>
var arr = ['Tea', 'Coffee', 'Milk'];
arr.pop();
console.log(arr.join(' - '));
</script>
</body>
</html>
result:
Now, we’ll try to use the “shift” and “unshift” method.
The “shift” and “unshift” method is the same as “pop” and “push” but it works with the first element in an array.
Example:
<!DOCTYPE html>
<html lang="en">
<head>
<title>Javascript Array</title>
</head>
<body>
<script>
var arr = ['Tea', 'Coffee', 'Milk'];
arr.unshift('Lemon');
console.log(arr.join(' - '));
</script>
</body>
</html>
result:
The “shift” will remove the first element.
Example:
<!DOCTYPE html>
<html lang="en">
<head>
<title>Javascript Array</title>
</head>
<body>
<script>
var arr = ['Tea', 'Coffee', 'Milk'];
arr.shift();
console.log(arr.join(' - '));
</script>
</body>
</html>
result:
The “shift” and “pop” completely eliminate the array element. It’s not like the example before that using the “undefined” to removing an element.
That’s the basic usage example of the array in javascript. You can find the full source code of these examples on our GitHub.
Thanks!
#javascript #web-development
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1624388400
JavaScript Arrays Tutorial. DO NOT MISS!!!
Learn JavaScript Arrays
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The origin of the article: https://www.youtube.com/watch?v=oigfaZ5ApsM&list=PLTjRvDozrdlxEIuOBZkMAK5uiqp8rHUax&index=4
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#arrays #javascript #javascript arrays #javascript arrays tutorial
1602147513
Now Learn JavaScript Programming Language With Microsoft
icrosoft has released a new series of video tutorials on YouTube for novice programmers to get a hands-on renowned programming language — JavaScript.
This isn’t the first attempt by Microsoft to come up with video tutorials by beginner programmers. The company also has a series of YouTube tutorials on Python for beginners.
For JavaScript, Microsoft has launched a series of 51 videos as ‘Beginner’s Series to JavaScript,’ for young programmers, developers and coders who are interested in building browser applications using JavaScript. These video tutorials will also help programmers and coders to use relevant software development kits (SDKs) and JavaScript frameworks, such as Google’s Angular.
“Learning a new framework or development environment is made even more difficult when you don’t know the programming language,” stated on the Microsoft Developer channel on YouTube. “Fortunately, we’re here to help! We’ve created this series of videos to focus on the core concepts of JavaScript.”
It further stated — while the tutorials don’t cover every aspect of JavaScript, it indeed will help in building a foundation from which one can continue to grow. By the end of this series, Microsoft claims that the novice programmers will be able to work through tutorials, quick starts, books, and other resources, continuing to grow on their own.
#news #javascript #javascript tutorial #javascript tutorials #microsoft tutorials on javascript
1608042336
JavaScript Shopping Cart - Javascript Project for Beginners
#shopping cart javascript #hopping cart with javascript #javascript shopping cart tutorial for beginners #javascript cart project #javascript tutorial #shopping cart
1600410360
Javascript Array From Example | Array.prototype.from()
Javascript array from() is an inbuilt function that creates a new, shallow-copied array instance from an array-like object or iterable object.
The Array .from() lets you develop Arrays from the array-like objects (objects with a length property and indexed items) or iterable objects ( objects where you can get its items, such as Map and Set).
The Array from() function was introduced in ECMAScript 2015.
Javascript Array From Example
Array.from() method in Javascript is used to creates a new array instance from a given array. If you pass a string to the Array.from() function, then, in that case, every alphabet of the string is converted to an element of the new array instance. In the case of integer values, a new array instance simply takes the elements of the given Array.
The syntax of the Array.from() method is the following.
Syntax
Array.from(arrayLike[, mapFn[, thisArg]])
#javascript #ecmascript #javascript array from #array.prototype.from
1602154740
Fill and Filter in Array in JavaScript
By the word Array methods, I mean the inbuilt array functions, which might be helpful for us in so many ways. So why not just explore and make use of them, to boost our productivity.
Let’s see them together one by one with some amazing examples.
Array.fill():
The
_fill()_method changes all elements in an array to a static value, from a start index (default_0_) to an end index (default_array.length_). It returns the modified array.
In simple words, it’s gonna fill the elements of the array with whatever sets of params, you pass in it. Mostly we pass three params, each param stands with some meaning. The first param value: what value you want to fill, second value: start range of index(inclusive), and third value: end range of index(exclusive). Imagine you are going to apply this method on some date, so that how its gonna look like eg: array.fill(‘Some date’, start date, end date).
NOTE: Start range is inclusive and end range is exclusive.
Let’s understand this in the below example-
//declare array
var testArray = [2,4,6,8,10,12,14];
console.log(testArray.fill("A"));
When you run this code, you gonna see all the elements of testArray will be replaced by 'A' like [“A”,"A","A","A","A","A","A"].
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