String
String is one the most important data-type of Javascript. Today we will try to explore some of the important methods of String.
charAt() method :
In this method, one can easily find out the character at a specified index in a string. In Javascript position is described as index. The first index of any string is ‘0’ and the last index is ‘string.length — 1’.
const str = ‘Bangladesh is my native country’;
console.log(str.charAt(7));
// the result will be — e
console.log(str.charAt());
// the result will be — 0
If you provide index is out of range, It will return empty string and not provided index charAt() the default value is 0.
concat() method:
It concatenate or link two or more things in a chain.
const str1 = ‘Hello’;
const str2 = ‘Bangladesh’;
console.log(str1.concat(‘ ‘, str2));
console.log(str1.concat(‘ ‘, ‘Bangladesh’)); // both the result will be Hello Bangladesh
indexOf() method:
In this method we can easily find out the position of any character or starting position of a word in string. Index in string is count from left to right.
const str = ‘Bangladesh is my native country’;
console.log(str.indexOf(‘my’));
// the result will be — 14
If the value is not found it returns -1.
lastIndexOf() method:
if there are same word or character contains two or more times in a string in this method we can find the last position of that word or character.
const str = ‘Bangladesh is my native country. Bangla is my favorite language’;
console.log(str.lastIndexOf(‘my’));
// the result will be — 43
Replace() method:
In this method, we can change any value from a string.
const str = ‘I like Banana’;
console.log(str.replace(‘Banana’, ‘Mango’));
// the result will be — ‘I like Mango’
Slice() method:
This method extracts value from a string and returns a new string. This method has to provide start and end parameters for specified the extracting position in string.
const str = ‘Hello Bangladesh’;
console.log(str.slice(0, 5));
// the result will be — Hello
Split() method:
In this method, a string is divided into substring and returns an array. In this method have to mention the separator.
const str = ‘I live in Bangladesh’;
const split = str.split( ‘ ‘);
console.log(split);
// the result will be [ ‘I’, ‘live’, ‘in’, ‘Bangladesh’ ]
If provide empty string (split(‘’)) as a separator then every single character will convert into a string.
Includes() method:
In this method determines whether a string contains specified character or not. If the character contains It returns true, if not false.
const str = ‘I live in Bangladesh’;
console.log(str.includes(‘live’));
// the result will be — true
console.log(str.includes(‘lives’));
// the result will be — false
toLowerCase() method:
This method converted the value of a string into lower case.
const str = ‘I Live In Bangladesh’;
console.log(str.toLowerCase());
// the result will be ‘i live in bangladesh’
toUpperCase() method:
This method converted the value of a string into upper case.
const str = ‘I Live In Bangladesh’;
console.log(str.toUpperCase());
// the result will be ‘I LIVE IN BANGLADESH’
