/**
 * Returns a new string based off `x`, in which the first character is put through `.toUpperCase()`,
 * and the remainder are put through `.toLowerCase()`
 *
 * If `x` is empty, returns empty string
 */
export declare const capitalize: (x?: string) => string;
/**
 * Splits the string using `toExtract`, then joins it using `toReplaceWith`.
 *
 * `toReplaceWith` defaults to `""`
 */
export declare const extract: (string: string, toExtract: string | RegExp, toReplaceWith?: string) => string;
/**
 * Counts the number of (non-intersecting) occurences of `substring` inside `string`
 */
export declare const count: (string: string, substring: string | RegExp) => number;
/**
 * Creates a function for limiting the `string` with `maxlength` length,
 * and (if the `.length` exceeds the `maxlength`), replacing the end with
 * the `limitor`
 */
export declare const limit: (maxlength: number, limitor?: string) => (string?: string) => string;
/**
 * Returns the entirety of the string, except for the last symbol
 */
export declare const lastOut: (x: string) => string;
/**
 * Concatenates the `strings`, and returns the result
 */
export declare const concat: (...strings: string[]) => string;
/**
 * Performs an algorithm of "covering" on the given strings, and returns the result.
 *
 * Covering on two strings `a, b` returns `a + b.slice(a.length)`,
 * that is, replacing the first `a.length` characters of `b` with `a`,
 * and concatenating the remainder.
 */
export declare const cover: (...strings: string[]) => string;
/**
 * A function returning whether the given string is empty.
 */
export declare const isEmpty: (x: string) => boolean;
/**
 * Returns the last index of a given string
 */
export declare const lastIndex: (x: string) => number;
/**
 * Returns `x.charCodeAt(i)`. `i` defaults to 0
 */
export declare const charCodeAt: (x: string, i?: number) => number;
/**
 * Consequently splits the given string `x` using `splitBy` delimiters, and returns the result.
 */
export declare const multiSplit: (x: string, splitBy: string[]) => string[];