01.JavaScript Function
Every JavaScript function is actually a “Function Object”. It is a block of code designed to perform a particular task. The function keyword goes first, then goes the function name, then a list of parameters.
Example:
function myFunction(a, b){
return a + b;
}
const result = myFunction(4, 6);
the result will be 10.
02.JavaScript Object
The concept of objects in JavaScript can be understood with real life. An object is a collection of properties, and a property is an association between a name and a value.
Example:
const person = {
name: “Riya”, age: “22”, job :“developer”
}
console.log(person);
Output will be : full object
03. JavaScript String slice()
The slice() method extracts parts of a string and returns the extracted parts in a new string. Use the start and end parameters to specify the part of the string you want to extract.
Example:
let start = “Bangladesh is a independence country.”;
let start1 = start.slice(6, 14);
console.log(start);
output will be: desh is a
04. JavaScript toUpperCase()
The toUpperCase() method converts a string to uppercase letters. The toUpperCsae() method does not change the original string.
Example:
const start = “Hi, my friend’s.”;
const result = start.toUpperCase();
console.log(result);
Output will be: “HI, MY FRIEND’S.”
05. JavaScript toLowerCase()
The toLowerCase() method converts a string to lowercase letters. the toLowerCase() method does not change the original string.
Example:
const start = “Hi, my friend’s.”;
const result = start.toLowerCase();
console.log(result);
Output will be: “hi, my friend’s.”
06. JavaScript Number()
The Number() function converts the object argument to a number that represents the object’s value. If a number cannot be converted to legal number, NaN is returned.
Example:
const start = “123”;
const result = Number(start);
console.log(result);
Output will be: 123
07. JavaScript Math
Math is built-in object. Unlike other global objects, the math object has no constructor. Methods and all properties are static.
Methods:
a.Math.round()
example:
Math.round(5.666); // return 6
Math.round(5.3456) // return 5
b.Math.floor()
example:
const start = “5.8”;
const result = Math.floor(start);
console.log(result);
Output will be: 5
c.Math.random()
example:
const start = “5”;
const result = Math.random(start);
console.log(result);
Output will be: 0.08662837937351209 a random number
08. JavaScript Array
An array is a special variable, which can hold more than one value at a time. An array can hold many values under a single name, and you can access the values using the index position, loop over an array, Add an item to the end of an array and so on.
Example:
let friends = [ ‘Riya’, ‘Priya’, ‘Anika’, ‘Ontora’, ‘Sayma’]
console.log(friends.length);
Output will be : 5
09. JavaScript filter()
The filter() calls a provided call back function. The filter() method creates a new array with all array elements that pass a test(provided as a function). filter() method does not change the original array.
Example:
const friends = [ ‘Riya’, ‘Priya’, ‘Anika’, ‘Ontora’, ‘Sayma’];
const newFriends = friends.filter(item => item.length > 5);
console.log(newFriends);
Output will be : ‘Ontora’
10.JavaScript map()
The map() method creates a new array with the results of calling a function for every array element. This method does not change the original array.
Example:
const number = [2, 3, 4, 5, 6, 7];
const newNumber = number.map(myFunction);
function myFunction(num){
return num * 2;
}
console.log(newNumber);
Output will be : [ 4, 6, 8, 10, 12, 14 ]
11.About http:// and https://
HTTP: http means Hyper Text Transfer Protocol. Communication between client computers and web servers is done by sending http requests and receiving http responses.
HTTPS: https means Hyper Transfer Protocol Secure is an extension of the Hypertext Transfer Protocol. It is used for secure communication over a computer network.
