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Javascript String Methods

Javascript String Methods

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Somanshu Grover
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Javascript has 18 string methods explained below

CharAt

Parameter: (index) defaults to 0 - (number data type) Return: character at specific index in the string (string data type) charAt accepts a index (number data type) and return the character on that index in the string. Example:

let name = 'Arya Stark';
name.charAt(2); //"y"
let sentance = 'A quick brown fox jumped over a lazy dog';
sentance(4); // "i"
let houseName = 'Starks';
houseName.charAt(0); // "S"

ToUpperCase

Parameter: string data type Return: uppercase of the string toUpperCase returns the value of the string converted to upper case Example:

let name = 'Arya Stark';
name.toUpperCase(); //'ARYA STARK'
let sentance = 'A quick brown fox jumped over a lazy dog';
sentance.toUpperCase() // 'A QUICK BROWN FOX JUMPED OVER A LAZY DOG'
let houseName = 'Starks';
houseName.toUpperCase(); //'STARKS'

ToLowerCase

Parameter: string data type Return: lowercase of the string toLowerCase returns the value of the string converted to lower case Example:

let name = 'ARYA STARK';
name.toUpperCase(); //'arya stark'
let sentance = 'A QUICK BROWN FOX JUMPED OVER A LAZY DOG';
sentance.toUpperCase() // ' a quick brown fox jumped over a lazy dog'
let houseName = 'STARKS';
houseName.toUpperCase(); //'starks'

Trim

Parameter: string data type Return: string without whitespace The trim() method removes whitespace from both ends of a string and returns a new string, without modifying the original string. Example:

let name = '   ARYA STARK           ';
name.trim(); // 'ARYA STARK'
let sentance = '                A QUICK BROWN FOX JUMPED OVER A LAZY DOG   ';
sentance.trim() // 'A QUICK BROWN FOX JUMPED OVER A LAZY DOG'
let houseName = '    STARKS                   ';
houseName.trim(); //'STARKS'

TrimEnd

Parameter: string data type Return: string without whitespace from the end The trim() method removes whitespace from ends of a string and returns a new string, without modifying the original string. Example:

let name = '   ARYA STARK           ';
name.trim(); // '    ARYA STARK'
let sentance = '                A QUICK BROWN FOX JUMPED OVER A LAZY DOG         ';
sentance.trim() // 'A QUICK BROWN FOX JUMPED OVER A LAZY DOG'
let houseName = '    STARKS                   ';
houseName.trim(); //'     STARKS'

TrimStart

Parameter: string data type Return: string without whitespace from the start The trim() method removes whitespace from start of a string and returns a new string, without modifying the original string. Example:

let name = '   ARYA STARK           ';
name.trim(); // 'ARYA STARK            '
let sentance = '                A QUICK BROWN FOX JUMPED OVER A LAZY DOG     ';
sentance.trim() // 'A QUICK BROWN FOX JUMPED OVER A LAZY DOG         '
let houseName = '    STARKS                   ';
houseName.trim(); //'STARKS                   '

Concat

Parameter: One or more strings to concatenate to str. (string data type) Return: A new string containing the combined text of the strings provided. The concat() method concatenates the string arguments to the calling string and returns a new string. Example:

let str1 = "somanshu";
let str2 = "grover";
str1.concat("  ", str2); // 'somanshu  grover'
str1.concat(" 56 ", str2); // 'somanshu 56 grover'
str1.concat(" eeeeee ", str2); // 'somanshu eeeeee grover'

EndsWith

Parameter:The characters to be searched for at the end of str.(string data type) length: If provided, it is used as the length of str. Defaults to str.length. Return: true if the given characters are found at the end of the string; otherwise, false. The endsWith() method determines whether a string ends with the characters of a specified string, returning true or false as appropriate. Example:

let str1 = "somanshu";
let str2 = "grover";
let str3 = str1 + str2 // 'somanshugrover'
str3.endsWith(`r`); // true
str3.endsWith(`R`); // false
str3.endsWith(`o`, 11); // true

Includes

Parameter:A string to be searched for within str.(string data type) position: The position within the string at which to begin searching for searchString. (Defaults to 0.) Return: true if the search string is found anywhere within the given string; otherwise, false if not.

  • The includes() method performs a case-sensitive search to determine whether one string may be found within another string, returning true or false as appropriate. Example:
    let sentance = 'A QUICK BROWN FOX JUMPED OVER A LAZY DOG';
sentance.includes(`fox`) //false
sentance.includes(FOX) // true sentance.includes(lazy DOG) // false

IndexOf

Parameter:Substring to search for. (string data type) position: The method returns the index of the first occurrence of the specified substring at a position greater than or equal to position, which defaults to 0. Return: The index of the first occurrence of searchString found, or -1 if not found. The indexOf() method, given one argument: a substring to search for, searches the entire calling string, and returns the index of the first occurrence of the specified substring. Given a second argument: a number, the method returns the first occurrence of the specified substring at an index greater than or equal to the specified number. Example:

let sentance = 'A QUICK BROWN FOX JUMPED OVER A LAZY DOG';
sentance.indexOf(`DOG`); // 37
sentance.indexOf(`dog`); // -1
sentance.indexOf(`BROWN`); // 8

LastIndexOf

Parameter:Substring to search for. (string data type) position: The method returns the index of the first occurrence of the specified substring at a position greater than or equal to position, which defaults to 0. Return: The index of the first occurrence of searchString found, or -1 if not found. The lastIndexOf() method, given one argument: a substring to search for, searches the entire calling string, and returns the index of the last occurrence of the specified substring. Given a second argument: a number, the method returns the last occurrence of the specified substring at an index less than or equal to the specified number. Example:

let sentance = 'A QUICK BROWN FOX JUMPED OVER A LAZY DOG';
sentance.lastIndexOf(`n`); //-1
sentance.lastIndexOf(`O`); //38
sentance.lastIndexOf(`A`); // 33

PadEnd

Parameter: targetLength- The length of the resulting string once the current str has been padded. If the value is lower than str.length, the current string will be returned as-is. padString Optional The string to pad the current str with. If padString is too long to stay within targetLength, it will be truncated: for left-to-right languages the left-most part and for right-to-left languages the right-most will be applied. The default value for this parameter is " " (U+0020). Return: A String of the specified targetLength with the padString applied at the end of the current str. The padEnd() method pads the current string with a given string (repeated, if needed) so that the resulting string reaches a given length. The padding is applied from the end of the current string. Example:

let name = `Somanshu Grover`;
name.padEnd(10); // 'Somanshu Grover'
name.padEnd(19); //'Somanshu Grover    '
name.padEnd(22, `.`); //'Somanshu Grover.......'
name.padEnd(22, `/`); //'Somanshu Grover///////'
name.padEnd(22, `g`); //'Somanshu Groverggggggg'

PadStart

Parameter: targetLength- The length of the resulting string once the current str has been padded. If the value is lower than str.length, the current string will be returned as-is. padString Optional The string to pad the current str with. If padString is too long to stay within targetLength, it will be truncated: for left-to-right languages the left-most part and for right-to-left languages the right-most will be applied. The default value for this parameter is " " (U+0020). Return: A String of the specified targetLength with the padString applied at the end of the current str. The padStart() method pads the current string with another string (multiple times, if needed) until the resulting string reaches the given length. The padding is applied from the start of the current string. Example:

let name = `Somanshu Grover`;
name.padStart(10); // 'Somanshu Grover'
name.padStart(19);//'    Somanshu Grover'
name.padStart(22, `.`);//'.......Somanshu Grover'
name.padStart(22, `/`);//'///////Somanshu Grover'
name.padStart(22, `g`);//'gggggggSomanshu Grover'

Repeat

Parameter:An integer between 0 and +Infinity, indicating the number of times to repeat the string. (number data type) Return:A new string containing the specified number of copies of the given string. The repeat() method constructs and returns a new string which contains the specified number of copies of the string on which it was called, concatenated together. Example:

let name = "Somanshu Grover";
name.repeat(2); //'Somanshu GroverSomanshu Grover'
name.repeat(5); // 'Somanshu GroverSomanshu GroverSomanshu GroverSomanshu GroverSomanshu Grover'
name.repeat(0); //''

Replace

Parameter:A string that is to be replaced by newSubstr. It is treated as a literal string and is not interpreted as a regular expression. Only the first occurrence will be replaced. Return:A new string, with some or all matches of a pattern replaced by a replacement. The replace() method returns a new string with some or all matches of a pattern replaced by a replacement. The pattern can be a string or a RegExp, and the replacement can be a string or a function called for each match. If pattern is a string, only the first occurrence will be replaced. Example:

sentance.replace("DOG", "monkey"); // 'A QUICK BROWN FOX JUMPED OVER A LAZY monkey'
sentance.replace("FOX", "elephant"); //'A QUICK BROWN elephant JUMPED OVER A LAZY DOG'
sentance.replace("FOX", "human"); //'A QUICK BROWN human JUMPED OVER A LAZY DOG'
sentance.replaceAll("O", "human"); //'A QUICK BRhumanWN FhumanX JUMPED humanVER A LAZY DhumanG'

Slice

Parameter: a string which is extracted from that number paramter ie number Return:A new string containing the extracted section of the string. -The slice() method extracts a section of a string and returns it as a new string, without modifying the original string. Example:

sentance.slice(23); //'D OVER A LAZY DOG'
sentance.slice(35);//'Y DOG'
sentance.slice(15);//'OX JUMPED OVER A LAZY DOG'

Split

Parameter: a string which is to be converted into array number and string Return:An Array of strings, split at each point where the separator occurs in the given string. The split() method divides a String into an ordered list of substrings, puts these substrings into an array, and returns the array. The division is done by searching for a pattern; where the pattern is provided as the first parameter in the method's call. Example:

name.split(" ");//(2) ['Somanshu', 'Grover']
name.split("", 10);//(10) ['S', 'o', 'm', 'a', 'n', 's', 'h', 'u', ' ', 'G']
name.split("u");//(2) ['Somansh', ' Grover']

Substring

Parameter: indexStart - The index of the first character to include in the returned substring. indexEnd -The index of the first character to include in the returned substring. Return:A new string containing the specified part of the given string. The substring() method returns the part of the string between the start and end indexes, or to the end of the string. Example:

name.substring(4);//'nshu Grover'
name.substring(1);//'omanshu Grover'
name.substring(1, 9);//'omanshu '
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