The String global object is a constructor for strings, or a sequence of characters.
The charAt() method returns the specified character from a string.
The charCodeAt() method returns an integer between 0 and 65535 representing the UTF-16 code unit at the given index (the UTF-16 code unit matches the Unicode code point for code points representable in a single UTF-16 code unit, but might also be the first code unit of a surrogate pair for code points not representable in a single UTF-16 code unit, e.g. Unicode code points > 0x10000). If you want the entire code point value, use codePointAt().
The concat() method combines the text of one or more strings and returns a new string.
The endsWith() method determines whether a string ends with the characters of another string, returning true or false as appropriate.
The static String.fromCharCode() method returns a string created by using the specified sequence of Unicode values.
The static String.fromCodePoint() method returns a string created by using the specified sequence of code points.
The includes() method determines whether one string may be found within another string, returning true or false as appropriate.
The indexOf() method returns the index within the calling String object of the first occurrence of the specified value, starting the search at fromIndex. Returns -1 if the value is not found.
The lastIndexOf() method returns the index within the calling String object of the last occurrence of the specified value, searching backwards from fromIndex. Returns -1 if the value is not found.
The length property represents the length of a string.
The padEnd() method pads the current string with a given string (eventually repeated) so that the resulting string reaches a given length. The pad is applied from the end (right) of the current string.
The padStart() method pads the current string with a given string (eventually repeated) so that the resulting string reaches a given length. The pad is applied from the start (left) of the current string.
The String.prototype property represents the String prototype object.
The static String.raw() method is a tag function of template literals, similar to the r prefix in Python or the @ prefix in C# for string literals (yet there is a difference: see explanations in this issue). It's used to get the raw string form of template strings (that is, the original, uninterpreted text).
The slice() method extracts a section of a string and returns a new string.
The deprecated substr() method returns the characters in a string beginning at the specified location through the specified number of characters.
The substring() method returns a subset of a string between one index and another, or through the end of the string.
The toLowerCase() method returns the calling string value converted to lower case.
The toString() method returns a string representing the specified object.