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# String Checking
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String-specific validation including case checking, content analysis, and format validation.
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## Capabilities
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### Case Validation
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#### Uppercase Check
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Checks if the given string is all uppercase.
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```javascript { .api }
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/**
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 * Checks if the given string is UPPERCASE
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 * @param value - String to check
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 * @returns True if string is all uppercase
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 * Interfaces: not, all, any
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 */
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function upperCase(value: string): boolean;
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```
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**Usage Example:**
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```javascript
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is.upperCase('YEAP');           // true
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is.upperCase('nope');           // false
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is.not.upperCase('Nope');       // true
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is.all.upperCase('YEAP', 'nope'); // false
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is.any.upperCase('YEAP', 'nope'); // true
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```
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#### Lowercase Check
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Checks if the given string is all lowercase.
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```javascript { .api }
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/**
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 * Checks if the given string is lowercase
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 * @param value - String to check
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 * @returns True if string is all lowercase
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 * Interfaces: not, all, any
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 */
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function lowerCase(value: string): boolean;
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```
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**Usage Example:**
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```javascript
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is.lowerCase('yeap');           // true
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is.lowerCase('NOPE');           // false
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is.not.lowerCase('Nope');       // true
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is.all.lowerCase('yeap', 'NOPE'); // false
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is.any.lowerCase('yeap', 'NOPE'); // true
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```
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#### Capitalized Check
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Checks if the given string is capitalized (each word starts with uppercase).
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```javascript { .api }
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/**
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 * Checks if the given string is capitalized
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 * @param value - String to check
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 * @returns True if string is capitalized
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 * Interfaces: not, all, any
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 */
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function capitalized(value: string): boolean;
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```
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**Usage Example:**
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```javascript
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is.capitalized('Yeap');         // true
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is.capitalized('nope');         // false
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is.not.capitalized('nope not capitalized'); // true
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is.all.capitalized('Yeap', 'All', 'Capitalized'); // true
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is.any.capitalized('Yeap', 'some', 'Capitalized'); // true
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```
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### Content Analysis
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#### Include Check
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Checks if the given string contains a substring.
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```javascript { .api }
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/**
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 * Checks if the given string contains a substring
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 * @param string - String to search in
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 * @param target - Substring to search for
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 * @returns True if string contains target
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 * Interfaces: not
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 */
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function include(string: string, target: string): boolean;
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```
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**Usage Example:**
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```javascript
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is.include('Some text goes here', 'text'); // true
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is.include('test', 'text');                 // false
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is.not.include('test', 'text');             // true
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```
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#### Start With Check
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Checks if the given string starts with a substring.
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```javascript { .api }
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/**
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 * Checks if the given string starts with substring
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 * @param string - String to check
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 * @param target - Substring to check for at start
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 * @returns True if string starts with target
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 * Interfaces: not
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 */
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function startWith(string: string, target: string): boolean;
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```
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**Usage Example:**
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```javascript
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is.startWith('yeap', 'ye');         // true
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is.startWith('nope', 'ye');         // false
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is.not.startWith('nope not that', 'not'); // true
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```
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#### End With Check
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Checks if the given string ends with a substring.
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```javascript { .api }
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/**
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 * Checks if the given string ends with substring
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 * @param string - String to check
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 * @param target - Substring to check for at end
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 * @returns True if string ends with target
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 * Interfaces: not
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 */
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function endWith(string: string, target: string): boolean;
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```
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**Usage Example:**
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```javascript
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is.endWith('yeap', 'ap');           // true
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is.endWith('nope', 'no');           // false
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is.not.endWith('nope not that', 'not'); // true
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is.endWith('yeap that one', 'one'); // true
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```
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### Pattern Analysis
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#### Palindrome Check
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Checks if the given string is a palindrome (reads the same forwards and backwards).
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```javascript { .api }
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/**
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 * Checks if the given string is palindrome
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 * @param value - String to check
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 * @returns True if string is palindrome
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 * Interfaces: not, all, any
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 */
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function palindrome(value: string): boolean;
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```
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**Usage Example:**
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```javascript
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is.palindrome('testset');           // true
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is.palindrome('A man, a plan, a canal - Panama!'); // true
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is.palindrome('nope');              // false
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is.not.palindrome('nope not palindrome'); // true
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is.all.palindrome('testset', 'tt'); // true
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is.any.palindrome('Yeap', 'some', 'testset'); // true
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```