@lutlelk-tools/string

A comprehensive string utility library for TypeScript/JavaScript with validation, transformation, formatting, encoding, and generation capabilities.

Installation

npm install @lutlelk-tools/string
# or
pnpm add @lutlelk-tools/string
# or
yarn add @lutlelk-tools/string

Usage

Import the entire package

import { toCamelCase, slugify, isEmail, mask } from '@lutlelk-tools/string'

toCamelCase('hello-world') // => "helloWorld"
slugify('Hello World!') // => "hello-world"
isEmail('[email protected]') // => true

Import specific functions (tree-shaking supported)

import { toKebabCase, capitalize, generateUUID } from '@lutlelk-tools/string'

toKebabCase('helloWorld') // => "hello-world"
capitalize('hello') // => "Hello"
generateUUID() // => "xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx"

API

Validation

isBlank(value: unknown): boolean

Check if value is blank (null, undefined, or empty string).

isBlank('') // => true
isBlank('   ') // => true
isBlank(null) // => true
isBlank('hello') // => false

isEmail(value: string): boolean

Check if value is a valid email address.

isEmail('[email protected]') // => true
isEmail('invalid-email') // => false

isUrl(value: string): boolean

Check if value is a valid URL.

isUrl('https://example.com') // => true
isUrl('not-a-url') // => false

isPhone(value: string, pattern?: RegExp): boolean

Check if value is a valid phone number.

isPhone('13800138000') // => true
isPhone('12345') // => false

isUUID(value: string): boolean

Check if value is a valid UUID.

isUUID('550e8400-e29b-41d4-a716-446655440000') // => true
isUUID('not-a-uuid') // => false

isHex(value: string): boolean

Check if value is a hexadecimal string.

isHex('ff00ff') // => true
isHex('xyz') // => false

isBase64(value: string): boolean

Check if value is a valid Base64 string.

isBase64('SGVsbG8gV29ybGQ=') // => true
isBase64('not-base64!') // => false

isJson(value: string): boolean

Check if value is valid JSON.

isJson('{"name":"John"}') // => true
isJson('not-json') // => false

isNumeric(value: string): boolean

Check if value is numeric.

isNumeric('123.45') // => true
isNumeric('abc') // => false

isAlpha(value: string): boolean

Check if value contains only letters.

isAlpha('hello') // => true
isAlpha('hello123') // => false

isAlphanumeric(value: string): boolean

Check if value contains only letters and numbers.

isAlphanumeric('hello123') // => true
isAlphanumeric('hello!') // => false

isLowercase(value: string): boolean

Check if value is all lowercase.

isLowercase('hello') // => true
isLowercase('Hello') // => false

isUppercase(value: string): boolean

Check if value is all uppercase.

isUppercase('HELLO') // => true
isUppercase('Hello') // => false

Query

startsWith(value: string, search: string, position?: number): boolean

Check if string starts with search string.

startsWith('hello world', 'hello') // => true
startsWith('hello world', 'world') // => false

endsWith(value: string, search: string, length?: number): boolean

Check if string ends with search string.

endsWith('hello world', 'world') // => true
endsWith('hello world', 'hello') // => false

includes(value: string, search: string, position?: number): boolean

Check if string contains search string.

includes('hello world', 'world') // => true
includes('hello world', 'test') // => false

contains(value: string, search: string): boolean

Check if string contains search string (alias for includes).

contains('hello world', 'world') // => true

equals(value: string, other: string, ignoreCase?: boolean): boolean

Check if two strings are equal.

equals('hello', 'hello') // => true
equals('hello', 'HELLO', true) // => true
equals('hello', 'HELLO') // => false

Case Conversion

toCamelCase(value: string): string

Convert string to camelCase.

toCamelCase('hello-world') // => "helloWorld"
toCamelCase('hello_world') // => "helloWorld"
toCamelCase('Hello World') // => "helloWorld"

toPascalCase(value: string): string

Convert string to PascalCase.

toPascalCase('hello-world') // => "HelloWorld"
toPascalCase('hello_world') // => "HelloWorld"

toKebabCase(value: string): string

Convert string to kebab-case.

toKebabCase('helloWorld') // => "hello-world"
toKebabCase('HelloWorld') // => "hello-world"

toSnakeCase(value: string): string

Convert string to snake_case.

toSnakeCase('helloWorld') // => "hello_world"
toSnakeCase('HelloWorld') // => "hello_world"

toCapitalCase(value: string): string

Convert string to Capital Case.

toCapitalCase('hello-world') // => "Hello World"
toCapitalCase('hello_world') // => "Hello World"

toSentenceCase(value: string): string

Convert string to sentence case.

toSentenceCase('HELLO WORLD') // => "Hello world"
toSentenceCase('hello world') // => "Hello world"

toLowerCase(value: string): string

Convert string to lowercase.

toLowerCase('HELLO WORLD') // => "hello world"

toUpperCase(value: string): string

Convert string to uppercase.

toUpperCase('hello world') // => "HELLO WORLD"

toTitleCase(value: string): string

Convert string to title case.

toTitleCase('hello world') // => "Hello World"
toTitleCase('HELLO WORLD') // => "Hello World"

Trimming

trim(value: string, chars?: string): string

Remove characters from both ends of string.

trim('  hello  ') // => "hello"
trim('---hello---', '-') // => "hello"
trim('***hello***', '*') // => "hello"

trimStart(value: string, chars?: string): string

Remove characters from start of string.

trimStart('  hello  ') // => "hello  "
trimStart('---hello---', '-') // => "hello---"

trimEnd(value: string, chars?: string): string

Remove characters from end of string.

trimEnd('  hello  ') // => "  hello"
trimEnd('---hello---', '-') // => "---hello"

Padding

pad(value: string, length: number, char?: string): string

Pad string on both sides.

pad('hello', 10) // => "  hello   "
pad('hello', 10, '*') // => "**hello***"

padStart(value: string, length: number, char?: string): string

Pad string at the start.

padStart('hello', 10) // => "     hello"
padStart('hello', 10, '0') // => "00000hello"

padEnd(value: string, length: number, char?: string): string

Pad string at the end.

padEnd('hello', 10) // => "hello     "
padEnd('hello', 10, '0') // => "hello00000"

Manipulation

truncate(value: string, length: number, omission?: string): string

Truncate string to specified length.

truncate('hello world', 5) // => "he..."
truncate('hello world', 8, '...') // => "hello..."
truncate('hello', 10) // => "hello"

repeat(value: string, count: number): string

Repeat string count times.

repeat('hello', 3) // => "hellohellohello"
repeat('ab', 2) // => "abab"

replace(value: string, search: string | RegExp, replacement: string): string

Replace first occurrence of search string.

replace('hello world', 'world', 'there') // => "hello there"
replace('hello world', /o/, 'a') // => "hella world"

replaceAll(value: string, search: string | RegExp, replacement: string): string

Replace all occurrences of search string.

replaceAll('hello world', 'l', 'x') // => "hexxo worxd"
replaceAll('hello world', /o/g, 'a') // => "hella warld"

slice(value: string, start?: number, end?: number): string

Extract section of string.

slice('hello world', 0, 5) // => "hello"
slice('hello world', 6) // => "world"
slice('hello world', -5) // => "world"

substring(value: string, start: number, end?: number): string

Extract characters from string between indices.

substring('hello world', 0, 5) // => "hello"
substring('hello world', 6) // => "world"

split(value: string, separator: string | RegExp, limit?: number): string[]

Split string into array.

split('hello world', ' ') // => ["hello", "world"]
split('a,b,c', ',') // => ["a", "b", "c"]

join(values: string[], separator?: string): string

Join array of strings.

join(['hello', 'world'], ' ') // => "hello world"
join(['a', 'b', 'c'], ',') // => "a,b,c"

reverse(value: string): string

Reverse string.

reverse('hello') // => "olleh"
reverse('world') // => "dlrow"

Character Operations

capitalize(value: string): string

Capitalize first character.

capitalize('hello') // => "Hello"
capitalize('hello world') // => "Hello world"

uncapitalize(value: string): string

Uncapitalize first character.

uncapitalize('Hello') // => "hello"
uncapitalize('Hello World') // => "hello World"

length(value: string): number

Get string length.

length('hello') // => 5
length('hello world') // => 11

size(value: string): number

Get string size (alias for length).

size('hello') // => 5

charAt(value: string, index: number): string

Get character at index.

charAt('hello', 0) // => "h"
charAt('hello', 4) // => "o"

charCodeAt(value: string, index: number): number

Get character code at index.

charCodeAt('hello', 0) // => 104
charCodeAt('hello', 4) // => 111

Position

indexOf(value: string, search: string, fromIndex?: number): number

Get index of first occurrence.

indexOf('hello world', 'world') // => 6
indexOf('hello world', 'test') // => -1

lastIndexOf(value: string, search: string, fromIndex?: number): number

Get index of last occurrence.

lastIndexOf('hello world hello', 'hello') // => 12
lastIndexOf('hello world', 'test') // => -1

Counting

count(value: string, search: string): number

Count occurrences of substring.

count('hello world hello', 'hello') // => 2
count('hello world', 'l') // => 3

countWords(value: string): number

Count words in string.

countWords('hello world') // => 2
countWords('  hello   world  ') // => 2

countChars(value: string, char: string): number

Count occurrences of character.

countChars('hello', 'l') // => 2
countChars('hello world', 'o') // => 2

Slicing

first(value: string, n?: number): string

Get first n characters.

first('hello world') // => "h"
first('hello world', 5) // => "hello"

last(value: string, n?: number): string

Get last n characters.

last('hello world') // => "d"
last('hello world', 5) // => "world"

initial(value: string, n?: number): string

Get all but last n characters.

initial('hello world') // => "hello worl"
initial('hello world', 6) // => "hello"

rest(value: string, n?: number): string

Get all but first n characters.

rest('hello world') // => "ello world"
rest('hello world', 6) // => "world"

nth(value: string, index: number): string

Get character at index.

nth('hello', 0) // => "h"
nth('hello', 4) // => "o"

Insert/Remove

insert(value: string, index: number, substring: string): string

Insert substring at index.

insert('hello world', 5, ' beautiful') // => "hello beautiful world"
insert('hello', 0, 'say ') // => "say hello"

remove(value: string, search: string | RegExp): string

Remove first occurrence.

remove('hello world', 'world') // => "hello "
remove('hello world', /o/) // => "hella world"

removeAll(value: string, search: string | RegExp): string

Remove all occurrences.

removeAll('hello world hello', 'hello') // => " world "
removeAll('hello world', /l/g) // => "heo word"

Extraction

before(value: string, search: string): string

Get substring before search string.

before('hello world', 'world') // => "hello "
before('hello world', 'test') // => "hello world"

after(value: string, search: string): string

Get substring after search string.

after('hello world', 'hello') // => " world"
after('hello world', 'test') // => ""

between(value: string, start: string, end: string): string

Get substring between start and end.

between('hello [world] test', '[', ']') // => "world"
between('hello (world) test', '(', ')') // => "world"

Splitting

words(value: string, pattern?: RegExp): string[]

Split string into words.

words('hello world') // => ["hello", "world"]
words('hello-world', /[-\s]+/) // => ["hello", "world"]

chars(value: string): string[]

Split string into characters.

chars('hello') // => ["h", "e", "l", "l", "o"]

lines(value: string): string[]

Split string into lines.

lines('hello\nworld') // => ["hello", "world"]
lines('hello\r\nworld') // => ["hello", "world"]

Template

template(value: string, data: Record<string, unknown>): string

Replace {{key}} placeholders.

template('Hello {{name}}!', { name: 'John' }) // => "Hello John!"
template('Age: {{age}}', { age: 30 }) // => "Age: 30"

interpolate(value: string, data: Record<string, unknown>): string

Replace ${key} placeholders.

interpolate('Hello ${name}!', { name: 'John' }) // => "Hello John!"
interpolate('Age: ${age}', { age: 30 }) // => "Age: 30"

format(value: string, ...args: unknown[]): string

Format string with positional arguments.

format('Hello {0}!', 'John') // => "Hello John!"
format('{0} + {1} = {2}', 1, 2, 3) // => "1 + 2 = 3"

Formatting

slugify(value: string): string

Convert string to URL-friendly slug.

slugify('Hello World!') // => "hello-world"
slugify('This is a Test') // => "this-is-a-test"

Escaping

escape(value: string): string

Escape HTML special characters.

escape('<div>hello</div>') // => "&lt;div&gt;hello&lt;/div&gt;"
escape('"hello"') // => "&quot;hello&quot;"

unescape(value: string): string

Unescape HTML special characters.

unescape('&lt;div&gt;hello&lt;/div&gt;') // => "<div>hello</div>"
unescape('&quot;hello&quot;') // => "\"hello\""

escapeRegExp(value: string): string

Escape special regex characters.

escapeRegExp('hello.world') // => "hello\\.world"
escapeRegExp('[test]') // => "\\[test\\]"

stripTags(value: string): string

Remove HTML tags.

stripTags('<div>hello</div>') // => "hello"
stripTags('<p>test</p>') // => "test"

stripHtml(value: string): string

Remove HTML and decode entities.

stripHtml('<div>hello</div>') // => "hello"
stripHtml('&amp;') // => "&"

Encoding

encodeBase64(value: string): string

Encode string to Base64.

encodeBase64('hello world') // => "aGVsbG8gd29ybGQ="
encodeBase64('你好') // => "5L2g5aW9"

decodeBase64(value: string): string

Decode Base64 string.

decodeBase64('aGVsbG8gd29ybGQ=') // => "hello world"
decodeBase64('5L2g5aW9') // => "你好"

encodeURI(value: string): string

Encode URI component.

encodeURI('hello world') // => "hello%20world"
encodeURI('你好') // => "%E4%BD%A0%E5%A5%BD"

decodeURI(value: string): string

Decode URI component.

decodeURI('hello%20world') // => "hello world"
decodeURI('%E4%BD%A0%E5%A5%BD') // => "你好"

Hash

hashCode(value: string): number

Get hash code of string.

hashCode('hello') // => 99162322
hashCode('world') // => 113318802

Generation

generateUUID(): string

Generate a random UUID.

generateUUID() // => "550e8400-e29b-41d4-a716-446655440000"

random(length?: number): string

Generate random alphanumeric string.

random() // => "aB3xY9zP2kL8mN4"
random(8) // => "xY9zP2kL"

randomNumeric(length?: number): string

Generate random numeric string.

randomNumeric() // => "1234567890123456"
randomNumeric(8) // => "12345678"

randomAlpha(length?: number): string

Generate random alphabetic string.

randomAlpha() // => "aBxYzPkLmN"
randomAlpha(8) // => "xYzPkLmN"

randomAlphaNumeric(length?: number): string

Generate random alphanumeric string (alias for random).

randomAlphaNumeric() // => "aB3xY9zP2kL8mN4"

randomHex(length?: number): string

Generate random hexadecimal string.

randomHex() // => "a3f2b9c4d8e1f6a7"
randomHex(8) // => "a3f2b9c4"

Masking

mask(value: string, visibleChars?: number, maskChar?: string): string

Mask string with visible characters at end.

mask('1234567890') // => "******7890"
mask('1234567890', 4, '*') // => "******7890"
mask('hello world', 2, '#') // => "#########ld"

maskEmail(email: string, maskChar?: string): string

Mask email address.

maskEmail('[email protected]') // => "jo******@example.com"
maskEmail('[email protected]', '#') // => "te**@example.com"

maskPhone(phone: string, maskChar?: string): string

Mask phone number.

maskPhone('13800138000') // => "138****8000"
maskPhone('1234567890', '#') // => "123####890"

Abbreviation

abbreviate(value: string, length?: number): string

Abbreviate string.

abbreviate('hello world') // => "hello worl."
abbreviate('hello', 10) // => "hello"

initials(value: string): string

Get initials from string.

initials('John Doe') // => "JD"
initials('hello world test') // => "hwt"

Case Swapping

swapCase(value: string): string

Swap case of all characters.

swapCase('Hello World') // => "hELLO wORLD"
swapCase('ABC') // => "abc"

Shuffling

shuffle(value: string): string

Shuffle characters in string.

shuffle('hello') // => "loleh" (random order)

Prefix/Suffix

ensurePrefix(value: string, prefix: string): string

Ensure string starts with prefix.

ensurePrefix('world', 'hello ') // => "hello world"
ensurePrefix('hello world', 'hello ') // => "hello world"

ensureSuffix(value: string, suffix: string): string

Ensure string ends with suffix.

ensureSuffix('hello', ' world') // => "hello world"
ensureSuffix('hello world', ' world') // => "hello world"

stripPrefix(value: string, prefix: string): string

Remove prefix if present.

stripPrefix('hello world', 'hello ') // => "world"
stripPrefix('world', 'hello ') // => "world"

stripSuffix(value: string, suffix: string): string

Remove suffix if present.

stripSuffix('hello world', ' world') // => "hello"
stripSuffix('hello', ' world') // => "hello"

Indentation

dedent(value: string): string

Remove common indentation.

dedent('  hello\n  world') // => "hello\nworld"

indent(value: string, indent?: string, count?: number): string

Add indentation to each line.

indent('hello\nworld', '  ') // => "  hello\n  world"
indent('hello\nworld', '  ', 2) // => "    hello\n    world"

wrap(value: string, width?: number, separator?: string): string

Wrap text to specified width.

wrap('hello world this is a test', 10)
// => "hello\nworld\nthis is a\ntest"

Utility

toString(value: StringInput): string

Convert value to string.

toString(123) // => "123"
toString(null) // => ""
toString(undefined) // => ""
toString(true) // => "true"

License

MIT