Short notes on JavaScript strings

Strings are very useful for holding data that can be represented in text form. Like other programming languages, strings are used to represent and manipulate a sequence of characters in JavaScript.

Some Strings methods and description:

charAt() :-

Returns the character at the specified index (position)

return 'cat'.charAt(2) // returns "t"
return 'dog'.charAt(0) // returns "d"

concat():-

Joins two or more strings, and returns a new joined

const str1 = "Ariful";
const str2 = "Sagor";
console.log(str1.concat(" ", str2));
// output: "Ariful Sagor"
console.log(str2.concat(", ", str1));
// output: "Sagor, Ariful"

includes():-

Checks whether a string contains the specified string/character

const sentence = 'The fox cut off it's tail.';
const word = 'fox';
console.log(`The word "${word}" ${sentence.includes(word) ? 'is' : 'is not'} in the sentence`);
// output: "The word "fox" is in the sentence"

endsWith():-

Checks whether a string ends with specified string/characters

const str1 = 'Dogs are worse';
console.log(str1.endsWith('worse'));
// output: true
const str2 = 'Is there any questions';
console.log(str2.endsWith('?'));
// output: false

lastIndexOf():-

Returns the position of the last found occurrence of a specified value in a string

const paragraph = 'This is earth, a great planet.';
const searchTerm = 'planet';
console.log(`The index of the first "${searchTerm}" from the end is ${paragraph.lastIndexOf(searchTerm)}`);
// output: "The index of the first "planet" from the end is 23"

replace():-

Searches a string for a specified value, or a regular expression, and returns a new string where the specified values are replaced

const p = 'Is that a dog?';
console.log(p.replace('dog', 'monkey'));
// expected output: "Is that a monkey?"

slice():

Extracts a part of a string and returns a new string

const str = 'The quick brown fox jumps over the lazy dog.';
console.log(str.slice(31));
// output: "the lazy dog."
console.log(str.slice(4, 19));
// output: "quick brown fox"
console.log(str.slice(-4));
// output: "dog."
console.log(str.slice(-9, -5));
// output: "lazy"

split():-

Splits a string into an array of substrings

const str = 'The horse ran very fast';
const words = str.split(' ');
console.log(words[3]);
// output: "very"
const chars = str.split('');
console.log(chars[8]);
// output: "e"

startsWith():-

Checks whether a string begins with specified characters

const str1 = 'Lets go tomorrow.';
console.log(str1.startsWith('Let'));
// output: true
console.log(str1.startsWith('Sat', 3));
// output: false

toLowerCase():-

Converts a string to lowercase letters, according to the host’s locale

const sentence = 'What a beautiful bird that is!';
console.log(sentence.toLowerCase());
// output: "what a beautiful bird that is!"

toUpperCase():-

Converts a string to uppercase letters, according to the host’s locale

const sentence = 'The quick brown fox jumped very fast.';
console.log(sentence.toUpperCase());
// expected output: "THE QUICK BROWN FOX JUMPED VERY FAST."

trim():-

Removes whitespace from both ends of a string

const greeting = '   I'm Sagor   ';
console.log(greeting);
// output: "   I'm Sagor   ";
console.log(greeting.trim());
// output: "I'm Sagor";

trimEnd():-

Removes whitespace from end of a string

const greeting = '   I'm Sagor   ';
console.log(greeting);
// expected output: "   I'm Sagor   ";
console.log(greeting.trimEnd());
// expected output: "   I'm Sagor";

trimStart():-

Removes whitespace from the beginning of a string

const greeting = '   I'm Sagor   ';
console.log(greeting);
// expected output: "   I'm Sagor   ";
console.log(greeting.trimStart());
// expected output: "I'm Sagor   ";

Usually a JavaScript developer has to work with all these tools almost every days. There are also more strings available in JavaScript. All these makes JavaScript a very suitable for developers to use in everyday work.