Wednesday, September 26, 2018

Frequently Used Array Examples - Javascript|Typescript

In this blog post, We are going to learn Array Examples in typescript and javascript
Frequently Used Array  Examples - Javascript|Typescript

The array is a collection of elements/objects stored under one name.  Size of the array is fixed. As you know there are requirements to find out element in an array of typescript.

You can check my post on Array Sort Object Examples 

Typescript Examples | Javascript Examples

Following is a list of frequently used array examples 

How to remove an element or object from Array

This example shows how to 
  • Delete / remove element from an array  using Array.prototype.splice function
  • First find an index of an element in an array using findIndex() function
  • remove element from array using splice() function
var arrayStrings = new Array("one", "two", "there", "four"); 
var deleteElement = "one";
let index = this.arrayStrings.findIndex(d => d === deleteElement); 
this.arrayStrings.splice(index, 1);
console.log(arrayStrings );
Output is

0: "two"
1: "there"
2: "four"

How to Create Statically typed array of functions or callbacks

  This example shows
  1. How to Create an array of interfaces 
  2. How to create a Type array of callbacks or functions
First Create a named function of an interface that accepts strings and returns void Create an array of interfaces
interface MyInterface {
    (name: string): void;
}
var mycallback: MyInterface[] = [];
console.log(mycallback)
Or We can also use a typed array literal syntax for creating an array of functions

var myNewFunction: { (name: string): void; } [];

How to retrieve last element or object from an array 

This example shows

  • last element of an array using array.length-1 function 
  • How to find the length of an array using Array.length-1 element 
  • Get the Last element of an array | array.pop() method

var arrayStrings = new Array("one", "two", "there", "four"); 
console.log(arrayStrings[arrayStrings.length-1] );
console.log(arrayStrings.pop() );
Output is
four
four

How to create a Static array in typescript class 

This example shows

  1. Create a Static private array of a class
  2. the getSize method returns the static array size using length function

class MyClass {
    private static stringArray: string[] = ["one", "two", "three","four"];
    getSize(): number {
        return MyClass.stringArray.length; 
    }
}
var myobject = new MyClass();
console.log(myobject.getSize());
Output is
3

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