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String Mutators

String mutators transform the input data before validation. All mutators are executed first, then validators run on the transformed data.

All Mutators​

toString()
uppercase()
lowercase()
capitalize()
titleCase()
camelCase()
pascalCase()
snakeCase()
kebabCase()
slug()
trim()
ltrim()
rtrim()
trimMultipleWhitespace()
padStart()
padEnd()
base64Encode()
base64Decode()
urlEncode()
urlDecode()
htmlEscape()
unescapeHtml()
reverse()
truncate()
repeat()
mask()
replace()
replaceAll()
append()
prepend()
toAlpha()
toAlphanumeric()
removeNumbers()
removeSpecialCharacters()
safeHtml()

Case Conversion​

toString()​

Convert value to string

v.string().toString()
// Input: 123 → Output: "123"

uppercase()​

Convert to uppercase

v.string().uppercase()
// Input: "hello" → Output: "HELLO"

lowercase()​

Convert to lowercase

v.string().lowercase()
// Input: "HELLO" → Output: "hello"

capitalize()​

Capitalize first letter

v.string().capitalize()
// Input: "hello world" → Output: "Hello world"

titleCase()​

Convert to title case

v.string().titleCase()
// Input: "hello world" → Output: "Hello World"

camelCase()​

Convert to camelCase

v.string().camelCase()
// Input: "hello world" → Output: "helloWorld"

pascalCase()​

Convert to PascalCase

v.string().pascalCase()
// Input: "hello world" → Output: "HelloWorld"

snakeCase()​

Convert to snake_case

v.string().snakeCase()
// Input: "hello world" → Output: "hello_world"

kebabCase()​

Convert to kebab-case

v.string().kebabCase()
// Input: "hello world" → Output: "hello-world"

slug()​

Convert to URL-friendly slug

v.string().slug()
// Input: "Hello World!" → Output: "hello-world"

Trimming & Padding​

trim(needle?)​

Trim whitespace or specified character

v.string().trim()        // Trim spaces
v.string().trim('*')     // Trim asterisks
// Input: "  hello  " → Output: "hello"

ltrim(needle?)​

Trim from left

v.string().ltrim()
// Input: "  hello" → Output: "hello"

rtrim(needle?)​

Trim from right

v.string().rtrim()
// Input: "hello  " → Output: "hello"

trimMultipleWhitespace()​

Trim multiple whitespace into single space

v.string().trimMultipleWhitespace()
// Input: "hello    world" → Output: "hello world"

padStart(length, char)​

Pad from start

v.string().padStart(10, '0')
// Input: "123" → Output: "0000000123"

padEnd(length, char)​

Pad from end

v.string().padEnd(10, '0')
// Input: "123" → Output: "1230000000"

Encoding & Decoding​

base64Encode()​

Base64 encode

v.string().base64Encode()
// Input: "hello" → Output: "aGVsbG8="

base64Decode()​

Base64 decode

v.string().base64Decode()
// Input: "aGVsbG8=" → Output: "hello"

urlEncode()​

URL encode

v.string().urlEncode()
// Input: "hello world" → Output: "hello%20world"

urlDecode()​

URL decode

v.string().urlDecode()
// Input: "hello%20world" → Output: "hello world"

htmlEscape()​

HTML escape

v.string().htmlEscape()
// Input: "<script>" → Output: "&lt;script&gt;"

unescapeHtml()​

Unescape HTML

v.string().unescapeHtml()
// Input: "&lt;script&gt;" → Output: "<script>"

String Manipulation​

reverse()​

Reverse string

v.string().reverse()
// Input: "hello" → Output: "olleh"

truncate(maxLength, suffix)​

Truncate to maximum length

v.string().truncate(10, "...")
// Input: "This is a long string" → Output: "This is..."

repeat(count)​

Repeat string N times

v.string().repeat(3)
// Input: "hello" → Output: "hellohellohello"

mask(start, end?, char)​

Mask part of string

v.string().mask(2, 4, '*')
// Input: "password" → Output: "pa****rd"

replace(search, replace)​

Replace substring or pattern

v.string().replace('world', 'universe')
// Input: "hello world" → Output: "hello universe"

replaceAll(search, replace)​

Replace all occurrences

v.string().replaceAll('l', 'L')
// Input: "hello" → Output: "heLLo"

append(suffix)​

Append text to the end

v.string().append('!')
// Input: "hello" → Output: "hello!"

prepend(prefix)​

Prepend text to the beginning

v.string().prepend('Mr. ')
// Input: "Smith" → Output: "Mr. Smith"

Advanced Mutators​

toAlpha()​

Keep only alphabetic characters

v.string().toAlpha()
// Input: "hello123world" → Output: "helloworld"

toAlphanumeric()​

Keep only alphanumeric characters

v.string().toAlphanumeric()
// Input: "hello@#$world" → Output: "helloworld"

removeNumbers()​

Remove numeric characters

v.string().removeNumbers()
// Input: "hello123world" → Output: "helloworld"

removeSpecialCharacters()​

Remove special characters

v.string().removeSpecialCharacters()
// Input: "hello@#$world" → Output: "hello world"

safeHtml()​

Remove HTML tags

v.string().safeHtml()
// Input: "<p>Hello</p>" → Output: "Hello"

Examples​

Chaining Mutators​

const schema = v.string()
  .trim()              // Remove whitespace
  .lowercase()         // Convert to lowercase
  .slug()              // Convert to slug
  .minLength(3);       // Validate length

const result = await validate(schema, "  Hello World!  ");
// Result: { isValid: true, data: "hello-world" }

Email Normalization​

const emailSchema = v.string()
  .trim()
  .lowercase()
  .email();

const result = await validate(emailSchema, "  USER@EXAMPLE.COM  ");
// Result: { isValid: true, data: "user@example.com" }

Text Sanitization​

const sanitizedSchema = v.string()
  .trim()
  .removeSpecialCharacters()
  .titleCase();

const result = await validate(sanitizedSchema, "  hello@#$world!  ");
// Result: { isValid: true, data: "Hello World" }

See Also​