Discussion the window The window interface represents the Dom documents. window object supported all browsers. it represents the browser window.
The window.closed property indecats which window closed or open. it returns voolean value. Example JS
if(window.opener && !window.opener.closed){
window.opener.location.href = "www.googletranslate.com"
}The console object shows browser debugging console. and this access is globally. the console has a different instance method. For Example:
console.log (For general output)
console.dir (displaying specfied js object)
console.count (showing the number of log how many line has been called)The document return the reference of the window. that's why we are showing title etc. For Example:
console.log(window.document.title)The function object provides methods of functions. Mainly function use a organized to reusable code in a block quotation code and perform a single action. Different way to write function. Here i explained five ways to write a function. These are
i. Function Declaration
ii. Function Expression
iii. Shorthand Method
iv. with Constructors
v. Arrow Functions- Function Declaration
A Most common way to define a function in javascript. function declare includes declaring function keyword function name parameter brackets and pair curly brackets. For Example -
function isEqual (num){
return num === 5;
}- Function Expression
Function expressions are cloesly same as the function declaration. using var, let, const to follow a function. One of the main advantages of the function expression easy to debugging a function. when a function faces to an error. For Example -
const Equal = function (a,b){
if(a===b){
console.log("All number is equal")
}
}- Shorthand function
Shorthand syntax are introduced with ES2015. it is quite similar the getter and setter. shorthand function easier to read. For Example -
const obj = {
items = [],
get(index){
return this.items[index]
},
set(...elements){
return this.items.push(...elements)
}
}
items.add("foo", "bar")
items.get()- Constructors
In Javascript constructor is a function create a object. Once of the most important part is the this and new keyword . here this keyword use when a object is created. and this object refer this. For Example -
function shoes(size,color){
this.size = size;
this.color = color;
}
const newPerson = new shoes(37, 'blue');
console.log(newPerson.size)
console.log(newPerson.color)- Arrow Function
Arrow Function is one of the most important and usages features introduced on ES6. It is allows to developers to create a function and cleaner way to contrary to the function declaration. For Example -
let sum = (a,b)=> a+b
function sum(a,b){
return a+b
}In this article, we learn the function of writing way. There are more ways to writing js function.
In javascript, an Array is a data structure technique that contains a list of elements to store a single variable. Array method's is a built in javascript function. This method we can apply to value changes or calculate the value. array method can be help us. Other wise writing the js function from stractch. Many JS methods are available. some Example write in below. First of all we want to know how to declare the array
- Array Declare with Literale
let MyArray = []- Array Declare with constructure
let mayArray = new Array()-
Javascript Array Methods
-
Map()
This method provies a new array.
const arr = [1,2,3,4,5]
const mapped = arr.map((ele)=>(ele + 5))
console.log(mapped) // [6,7,8,9,10]- Filter()
This method return a new array are equal the following the condition.
const arr = [2,4,5,6,7,8,9,10,11]
const filtered = arr.filter((item)=>item % 2=== 0)
console.log(filtered); //[ 2, 4, 6, 8, 10 ]-
Sort()
This method are using for sorting data. ascending or descending order
const arr = [2,4,5,6,7,8,9,10,11]
const sorted = arr.sort((a,b)=>(b-a))
console.log(sorted); //[ 11, 10, 9, 8, 7, 6, 5, 4, 2]- forEach()
The mehtod are helps to loop an array
const arr = [2,4,5,6,7,8,9]
arr.forEach((value)=>{
console.log(value);
})- Concat()
This mehtod are using to merge two or more arrays and return a single array.
const arr1 = ["a", "b", "c", "d", "e"]
const arr2 = ["f", "g", "h", "i", "j"]
const concatArray = arr1.concat(arr2)
console.log(concatArray); //['a', 'b', 'c', 'd', 'e', 'f', 'g', 'h','i', 'j']
```js
const arr = [1, 2, 3, 4, 5]
const everyArray = arr.every((item)=>item <=3)
console.log(everyArray); //false- Includes
The method check the pass value return true of false
const arr = [1, 2, 3, 4, 5]
const result = arr.includes(2)
console.log(result);// True- Join()
this method return a new array and concating the array elements
const arr = ["a", "b", "c", "d", "e", "f"]
const result = arr.join("")
console.log(result); //abcdef- Reduce()
This method applyis a function on accumulator and current value
const arr = [1,2,3,4,5,6,7,8,9]
const reduced = arr.reduce((acc, cur)=>acc + cur )
console.log(reduced);// 45A callback is an important part of js programming language. A callback function is a function that is passed in argument to another function. The callback function called the outer the function to action. An example here we show a callback function -
const mainFunction = (callback)=>{
console.log("operation is start");
setTimeout(()=>{
callback("Operation is Complete");
},1000)
}
const callbackFunction = (result)=>{
console.log("Result : " + result);
}
mainFunction(callbackFunction);Programming languages are very useful for repetitive task from multiple calculations. we can see a scenario and take a simple idea how to work the loop.
Now we can see the different types of loop collection on array. First of all we can the for loop.
- For loop
The for loop is iterative statement. which we use to check certain condition and then repetadly executed the block of code. for loop syntax
for (initialExpression; condition; updateExpression) {
// for loop body: statement
}Example -
for (var i = 0; i < 3; i++) {
let name = "Nayem";
console.log("Hi, my name is " + name);
}- For .. of loop
const lang = ["js", "python", "Go", "Ruby & Rails", "Perl"]
for (let language of lang){
console.log(language);
}- map() & filter()
map()
const lang = ["js", "python", "Go", "Ruby & Rails", "Perl"]
const res = lang.map((item, i)=>{
console.log(`The language are ${i} : ${item}`);
})
Expected answer:
//The language are 0 : js
//The language are 1 : python
//The language are 2 : Go
//The language are 3 : Ruby & Rails
//The language are 4 : Perl//filter()
const lang = ["js", "python", "Go", "Ruby & Rails", "Perl"]
const res = lang.filter((item)=>{
console.log(`This language are exist Result: ${item.endsWith("s")}`);
})
Expected answer:
//This language are exist Result: true
//This language are exist Result: false
//This language are exist Result: false
//This language are exist Result: true
//This language are exist Result: false- while and Do while... loop
while loop syntex:
initializer
while (condition) {
// code to run
final-expression
}
let i= 0
while (i<5){
console.log(i)
i++
}- break loop
for(let i=0;i<=5;i++){
if(i === 3){
break;
}
console.log(i);
}
Expected answer:
//0
//1
//2- continue loop
for(let i=0;i<=5;i++){
if(i === 3){
continue;
}
console.log(i);
}
Expected loop
//0
//1
//2
//4
//5