# String

### length <sub>number</sub>

### at(index) <sub>function</sub>

Return the character (or surrogate pair) at the specified index, with support
for negative indices (counting from the end). If the index is out of range,
returns undefined.



**index**: The position of the character to return (can be negative).


**Returns**: A string of length 1 representing the character, or undefined if out of range.


### charCodeAt(index) <sub>function</sub>

Return a number indicating the UTF-16 code unit value at the given index.
If the index is out of range, returns NaN.



**index**: An integer between 0 and string length - 1.


**Returns**: An integer in the range [0, 65535] or NaN if out of range.


### charAt(index) <sub>function</sub>

Return a string consisting of the single UTF-16 code unit at the given index.
If the index is out of range, returns an empty string.



**index**: The zero-based index of the desired character.


**Returns**: The single-character string at the specified index, or '' if out of range.


### concat(stringN) <sub>function</sub>

Concatenate the provided string arguments to the current string and return a
new string.



**stringN**: One or more strings to concatenate.


**Returns**: A new string formed by joining the caller with the provided arguments.


### codePointAt(position) <sub>function</sub>

Return a non-negative integer that is the Unicode code point value at the
given position. Supports code points above 0xFFFF. Returns undefined if index
is out of range.



**position**: The index in the string (can be surrogate pairs).


**Returns**: The code point value, or undefined if out of range.


### isWellFormed() <sub>function</sub>

Return a boolean indicating whether the string is valid Unicode.
If it contains unpaired surrogate code points, return false.



**Returns**: True if the string is well-formed UTF-16, otherwise false.


### toWellFormed() <sub>function</sub>

Return a new string in which any unpaired surrogate code points have been
replaced by the Unicode replacement character U+FFFD.



**Returns**: A well-formed UTF-16 version of the string.


### indexOf(searchValue, fromIndex) <sub>function</sub>

Return the zero-based index of the first occurrence of 'searchValue' in the
string, starting at 'fromIndex'. If not found, return -1.



**searchValue**: The substring to search for.

**fromIndex**: The index at which to begin searching (default 0).


**Returns**: The index of the first match, or -1 if not found.


### lastIndexOf(searchValue, fromIndex) <sub>function</sub>

Return the zero-based index of the last occurrence of 'searchValue' in the
string, searching backwards from 'fromIndex'. If not found, return -1.



**searchValue**: The substring to search for.

**fromIndex**: The index at which to begin the backward search (defaults to string length - 1).


**Returns**: The index of the last match, or -1 if not found.


### includes(searchString, position) <sub>function</sub>

Return a boolean indicating whether 'searchString' appears within this string.
An optional position can be provided to start searching.



**searchString**: The substring to search for.

**position**: The position from which to begin searching (default 0).


**Returns**: True if the substring is found, otherwise false.


### endsWith(searchString, length) <sub>function</sub>

Return a boolean indicating whether the string ends with 'searchString'.
An optional 'length' can be provided to treat the string as if it were only
that long.



**searchString**: The substring to search for at the end.

**length**: An optional length to truncate the string before testing.


**Returns**: True if the string ends with 'searchString', otherwise false.


### startsWith(searchString, position) <sub>function</sub>

Return a boolean indicating whether the string begins with 'searchString'.
An optional position can be provided to start checking at that index.



**searchString**: The substring to search for at the start.

**position**: The index in the string to start searching (default 0).


**Returns**: True if the string starts with 'searchString', otherwise false.


### match(regexp) <sub>function</sub>

Use a regular expression to match the string. If 'regexp' is not a RegExp, it
is converted to one. Return an array of matches or null if none found.



**regexp**: The pattern to match (RegExp or string).


**Returns**: An array of matches or null.


### matchAll(regexp) <sub>function</sub>

Return an iterator of all RegExp match objects found within the string.
If 'regexp' is not a global or sticky RegExp, a TypeError is thrown.



**regexp**: The global/sticky RegExp to match over this string.


**Returns**: An iterator of match arrays.


### search(regexp) <sub>function</sub>

Use a regular expression to search for a match within the string. Return the
index of the first match, or -1 if no match is found.



**regexp**: A RegExp or string. If a string, it is converted to RegExp.


**Returns**: The index of the first match, or -1 if not found.


### split(separator, limit) <sub>function</sub>

Split the string into an array of substrings using 'separator' (RegExp or
string). An optional 'limit' can be provided to limit the number of splits.



**separator**: A string or RegExp used to divide the string.

**limit**: Maximum number of splits to include in the result array.


**Returns**: An array of the split substrings.


### substring(start, end) <sub>function</sub>

Return the substring between 'start' and 'end'. Indices outside the range
are clamped. If 'end' < 'start', they swap.



**start**: The starting index (0-based).

**end**: The ending index (exclusive).


**Returns**: The extracted substring.


### substr(start, length) <sub>function</sub>

Return the substring from 'start' for 'length' characters. Negative 'start'
counts from the end. This method is deprecated but still supported in many
engines.



**start**: The starting index.

**length**: The number of characters to extract.


**Returns**: The extracted substring.


### slice(start, end) <sub>function</sub>

Extract a section of the string from 'start' up to (but not including) 'end',
and return it as a new string. Supports negative indices.



**start**: The starting index. Negative values count from the end.

**end**: The ending index (exclusive). Negative values count from the end.


**Returns**: The extracted slice.


### repeat(count) <sub>function</sub>

Construct and return a new string which contains the specified number of copies
of the calling string, concatenated together.



**count**: The number of times to repeat the string (must be >= 0).


**Returns**: A new repeated string.


### replace(searchValue, replaceValue) <sub>function</sub>

Return a new string where the first match (or all matches if 'searchValue'
is a global RegExp) of 'searchValue' is replaced by 'replaceValue'.
If 'searchValue' is a string, only the first occurrence is replaced.



**searchValue**: A string or RegExp to match.

**replaceValue**: The replacement string or function.


**Returns**: A new string with the matched substring(s) replaced.


### replaceAll(searchValue, replaceValue) <sub>function</sub>

Return a new string where all (non-overlapping) occurrences of 'searchValue'
are replaced by 'replaceValue'. If 'searchValue' is a string, each exact match
is replaced.



**searchValue**: A string or RegExp with the 'g' flag.

**replaceValue**: The replacement string or function.


**Returns**: A new string with all matches replaced.


### padEnd(maxLength, padString) <sub>function</sub>

Pad the string from the end with the given 'padString' so its length reaches
'maxLength'. The result is a new string.



**maxLength**: The desired length of the resulting string.

**padString**: The string to pad with (default ' ').


**Returns**: A new string padded at the end.


### padStart(maxLength, padString) <sub>function</sub>

Pad the string from the start with the given 'padString' so its length reaches
'maxLength'. The result is a new string.



**maxLength**: The desired length of the resulting string.

**padString**: The string to pad with (default ' ').


**Returns**: A new string padded at the start.


### trim() <sub>function</sub>

Return a new string with whitespace trimmed from the start and end of this
string.



**Returns**: The trimmed string.


### trimEnd() <sub>function</sub>

Alias for trimEnd(). Remove trailing whitespace from the string.



**Returns**: The string without trailing whitespace.


### trimRight() <sub>function</sub>

Alias for trimEnd(). Remove trailing whitespace from the string.



**Returns**: The string without trailing whitespace.


### trimStart() <sub>function</sub>

Alias for trimStart(). Remove leading whitespace from the string.



**Returns**: The string without leading whitespace.


### trimLeft() <sub>function</sub>

Alias for trimStart(). Remove leading whitespace from the string.



**Returns**: The string without leading whitespace.


### toString() <sub>function</sub>

Return a string representing the specified object (itself). Usually called
implicitly. Overrides Object.prototype.toString.



**Returns**: The string itself.


### valueOf() <sub>function</sub>

Return the primitive string value of this String object.



**Returns**: The primitive string value.


### __quote() <sub>function</sub>

(Non-standard) Return a quoted representation of the string, typically for
debug or serialization. Implementation details may vary.



**Returns**: A quoted version of the string.


### localeCompare(compareString) <sub>function</sub>

Return a number indicating whether this string is less than, equal to, or
greater than 'compareString' in sort order, according to the current locale.



**compareString**: The string to compare against.


**Returns**: A negative number if less, 0 if the same, or a positive number if greater.


### toLowerCase() <sub>function</sub>

Return a new string with all alphabetic characters converted to lowercase.



**Returns**: The lowercase version of this string.


### toUpperCase() <sub>function</sub>

Return a new string with all alphabetic characters converted to uppercase.



**Returns**: The uppercase version of this string.


### toLocaleLowerCase() <sub>function</sub>

Return a locale-aware lowercase version of this string, using the host's
current locale or the specified locale if supported.



**Returns**: The locale-sensitive lowercase string.


### toLocaleUpperCase() <sub>function</sub>

Return a locale-aware uppercase version of this string, using the host's
current locale or the specified locale if supported.



**Returns**: The locale-sensitive uppercase string.


### anchor(name) <sub>function</sub>

Return a string representing an HTML <a> element with a 'name' attribute
set to the current string.



**name**: The name attribute for the anchor.


**Returns**: An HTML <a name="...">...</a> string.


### big() <sub>function</sub>

Return a string representing an HTML <big> element containing the current
string.



**Returns**: An HTML <big>...</big> string.


### blink() <sub>function</sub>

Return a string representing an HTML <blink> element containing the current
string (historical, not recommended).



**Returns**: An HTML <blink>...</blink> string.


### bold() <sub>function</sub>

Return a string representing an HTML <b> element containing the current
string in bold.



**Returns**: An HTML <b>...</b> string.


### fixed() <sub>function</sub>

Return a string representing an HTML <tt> element containing the current
string in fixed-width font.



**Returns**: An HTML <tt>...</tt> string.


### fontcolor(color) <sub>function</sub>

Return a string representing an HTML <font> element with a 'color' attribute,
containing the current string.



**color**: The color value for the 'font' element.


**Returns**: An HTML <font color="...">...</font> string.


### fontsize(size) <sub>function</sub>

Return a string representing an HTML <font> element with a 'size' attribute,
containing the current string.



**size**: The size value for the 'font' element.


**Returns**: An HTML <font size="...">...</font> string.


### italics() <sub>function</sub>

Return a string representing an HTML <i> element containing the current
string in italics.



**Returns**: An HTML <i>...</i> string.


### link(url) <sub>function</sub>

Return a string representing an HTML <a> element with an 'href' attribute set
to the current string.



**url**: The URL for the 'href' attribute.


**Returns**: An HTML <a href="...">...</a> string.


### small() <sub>function</sub>

Return a string representing an HTML <small> element containing the current
string.



**Returns**: An HTML <small>...</small> string.


### strike() <sub>function</sub>

Return a string representing an HTML <strike> element containing the current
string with strike-through.



**Returns**: An HTML <strike>...</strike> string.


### sub() <sub>function</sub>

Return a string representing an HTML <sub> element containing the current
string as subscript.



**Returns**: An HTML <sub>...</sub> string.


### sup() <sub>function</sub>

Return a string representing an HTML <sup> element containing the current
string as superscript.



**Returns**: An HTML <sup>...</sup> string.


### rm(index, endidx) <sub>function</sub>

Remove characters from this string between 'index' (inclusive)
and 'endidx' (exclusive). If 'endidx' is omitted, it defaults to 'index + 1'.



**index**: The starting index to remove.

**endidx**: The ending index (exclusive).


**Returns**: A new string with the specified characters removed.


### tolast(val) <sub>function</sub>

Return the substring of this string up to the last occurrence of 'val'.
If 'val' is not found, the entire string is returned.



**val**: The substring to locate from the end.


**Returns**: A substring up to the last occurrence of 'val'.


### dir() <sub>function</sub>

Return everything before the last slash ('/') in the string.
If no slash is found, return an empty string.



**Returns**: The directory portion of the path.


### next(char, from) <sub>function</sub>

Search for the next occurrence of 'char' in this string, starting at 'from'.
If 'char' is an array, any of those characters qualifies. Return the matching index,
or -1 if none is found.



**char**: A character (or array of characters) to locate.

**from**: The index to start from.


**Returns**: The index of the next occurrence, or -1 if not found.


### prev(char, from, count) <sub>function</sub>

Search for the previous occurrence of 'char' before index 'from'.
If 'count' is greater than 1, skip multiple occurrences going backward.
Return the found index or 0 if not found.



**char**: The character to locate.

**from**: The index to start from (defaults to the end of the string).

**count**: How many occurrences to skip backward (default 0).


**Returns**: The index of the previous occurrence, or 0 if not found.


### strip_ext() <sub>function</sub>

Return the string up to (but not including) the last '.' character.
If '.' is not found, the entire string is returned.



**Returns**: The string without its last extension.


### ext() <sub>function</sub>

Return the substring after the last '.' in this string.
If '.' is not found, return an empty string.



**Returns**: The file extension or an empty string.


### up_path() <sub>function</sub>

Go up one directory level from the current path, preserving the file name at the end.



**Returns**: A new path string one directory up, with the base filename preserved.


### fromlast(val) <sub>function</sub>

Return the substring that appears after the last occurrence of 'val'.
If 'val' is not found, an empty string is returned.



**val**: The substring to locate.


**Returns**: The substring after the last occurrence of 'val'.


### tofirst(val) <sub>function</sub>

Return the substring from the start of this string up to the first occurrence
of 'val' (excluded). If 'val' is not found, the entire string is returned.



**val**: The substring to locate.


**Returns**: A substring up to the first occurrence of 'val'.


### fromfirst(val) <sub>function</sub>

Return the substring after the first occurrence of 'val'.
If 'val' is not found, the entire string is returned.



**val**: The substring to locate.


**Returns**: The substring after 'val', or the entire string if 'val' not found.


### name() <sub>function</sub>

Return the "name" portion of the path without extension.
If no slash is found, it's up to the last '.' in the entire string.
If there is a slash, it's from the last slash up to (but not including) the last '.'.



**Returns**: The name portion of the path without extension.


### set_name(name) <sub>function</sub>

Set the base name (excluding extension) of the path to 'name', preserving
the original directory and extension.



**name**: The new name to use.


**Returns**: A new path string with the updated name.


### base() <sub>function</sub>

Return the portion of this string after the last '/' character.
If no '/' is present, the entire string is returned.



**Returns**: The base name of the path.


### updir() <sub>function</sub>

Go up one directory from the current path, removing the last directory name.
If the path ends with a slash, remove it first. Then remove the final directory.



**Returns**: A new string representing one directory level up.