Re-Take & Overview JavaScript
Concat()
- Concat is the built-in method of javascript languages
- When two string are added then javascript used concatenate function
- Concatenate string output value return is a new string value.
- Example Below:
const firstName = “Nasir”;
const lastName = “Uddin”;
const hello = “Hello”;
const how = “How are you”;
console.log(hello.concat(“ “ + firstName + “ “ + lastName + “ “).concat(how));
IndexOf()
- When we are fined any word from our string we use indexOf()
- IndexOf() is a built-in function
- Getting the string position your search that.
- This function is used for getting items from the array, string, and number
- When the search word can’t find from string indexOf() are return (-1)
- How to use indexOf() function.
- Example Below
const love = “I love Bangladesh”;
console.log(love.indexOf(“Bangladesh”));
const bangladesh = “Bangladesh”;
const getLove = love.indexOf(bangladesh);
console.log(getLove);
Slice
- Slice gives a new string from the base string.
- we need to slice when we are taking a small part of the array, objects, and string from a single word
- Slice is a built-in function and it’s using the start & end method for slicing
- Below the example:
const word = “I want to be a good developer. I will hard work “;
const word1 = word.slice(13, 29);
const word2 = word.slice(13, -1);
console.log(word1);
console.log(word2);
ParseInt
- When we any number are takin with string then we are converted this string and getting integer value.
- Example Below:
const number = “353”;
console.log(number);
console.log(parseInt(number));
console.log(parseInt(0xf, 16));
Math.ceil()
- Math ceil is static method for set the number value
- Math ceil is not a constructor function
- Example Below:
console.log(Math.ceil(0.85));
console.log(Math.ceil(0.6));
console.log(Math.ceil(0.3));
console.log(Math.ceil(0.45));
Math.Round()
- Math round is dynamic method for round the integer numbers
- Math round following when integer number nearest to .50 convert that integer 0
- Math round are created integer when the integer up to .50 then it self created integer 1.
- Example below:
console.log(Math.round(0.48));
console.log(Math.round(0.5));
console.log(Math.round(0.55));
console.log(Math.round(0.9));
Array.Map()
- The map always returns one for each element from an array. The map provides a callback function. It’s created a new constructor array.
- Example Below:
const arr = [
{
id: 1,
name: “name”,
address: “address”,
phone: 1233,
job: “developer”,
country: “country”,
},
{
id: 1,
name: “name”,
address: “address”,
phone: 1233,
job: “developer”,
country: “country”,
},
{
id: 1,
name: “name”,
address: “address”,
phone: 1233,
job: “developer”,
country: “country”,
},
{
id: 1,
name: “name”,
address: “address”,
phone: 1233,
job: “developer”,
country: “country”,
},
{
id: 1,
name: “name”,
address: “address”,
phone: 1233,
job: “developer”,
country: “country”,
},
{
id: 1,
name: “name”,
address: “address”,
phone: 1233,
job: “developer”,
country: “country”,
},
{
id: 1,
name: “name”,
address: “address”,
phone: 1233,
job: “developer”,
country: “country”,
},
{
id: 1,
name: “name”,
address: “address”,
phone: 1233,
job: “developer”,
country: “country”,
},
{
id: 1,
name: “name”,
address: “address”,
phone: 1233,
job: “developer”,
country: “country”,
},
];
const newArr = arr.map((user) => user.name);
console.log(newArr);
Array.find()
- Find method immediately returns the value of element from an array. then matching the targeted value from the array & return result.
- Example Below:
const number = [5, 12, 80, 130, 44];
const findNumber = number.find((num) => num > 80);
console.log(findNumber);
Array.pop()
- Pop are used for remove the last word from array.
- Example Below:
const friends = [“Rohim”, “korim”, “Jabbar”, “Akkas”, “Babol”];
console.log(friends);
const removeFriend = friends.pop();
console.log(removeFriend);
console.log(friends);
Array.shift()
- Shift methods are used for remove the first element form array.
- Example Below:
const user = [“Adol”, “Badol”, “Kadol”, “Jodol”];
console.log(user);
const shiftUser = user.shift();
console.log(shiftUser);
console.log(user);