String methods

Provides a reference for string methods.

Characters in a string are indexed from left to right. The index of the first character in a string is 0, and the index of the last character is string.length-1.

Table 1. String methods
Syntax	Effect
string.substring(start [ , end ] )	Returns the substring of `string` starting at the index `start` and ending at the index `end-1`. If `end` is omitted, the tail of `string` is returned. Examples: "0123456".substring(0, 3) –> "012" "0123456".substring(2, 4) –> "23" "0123456".substring(2) –> "23456"
string.charAt(index)	Returns a one-character string containing the character at the specified index of string. If `index` is out of range, an empty string is returned. Examples: "abcdef".charAt(0) –> "a" "abcdef".charAt(3) –> "d" "abcdef".charAt(100) –> ""
string.charCodeAt(index)	Returns the ASCII code of the character at the specified index of `string`. If`index` is out of range, returns NaN. Examples: "abcdef".charCodeAt(0) –> 97 "abcdef".charCodeAt(3) –> 100 "abcdef".charCodeAt(100) –> NaN
string.indexOf(substring [ , index ] )	Returns the index in `string` of the first occurrence of `substring`. The string is searched starting at `index`. If `index` is omitted, `string` is searched from the beginning. This method returns -1 if `substring` is not found. Examples: "abcdabcd".indexOf("bc") –> 1 "abcdabcd".indexOf("bc", 1) –> 1 "abcdabcd".indexOf("bc", 2) –> 5 "abcdabcd".indexOf("bc", 10) –> -1 "abcdabcd".indexOf("foo") –> -1 "abcdabcd".indexOf("BC") –> -1
string.lastIndexOf(substring [ , index ] )	Returns the index in `string` of the last occurrence of `substring`, when `string` is searched backwards, starting at `index`. If `index` is omitted, `string` is searched from the end. This method returns `-1` if `substring` is not found. Examples: "abcdabcd".lastIndexOf("bc") –> 5 "abcdabcd".lastIndexOf("bc", 5) –> 5 "abcdabcd".lastIndexOf("bc", 4) –> 1 "abcdabcd".lastIndexOf("bc", 0) –> -1 "abcdabcd".lastIndexOf("foo") –> -1 "abcdabcd".lastIndexOf("BC") –> -1
string.toLowerCase()	Returns `string` converted to lowercase. Example: "Hello, World".toLowerCase() "hello, world"
string.toUpperCase()	string.toUpperCase() Returns `string` converted to uppercase. Example: "Hello, World".toUpperCase() "HELLO, WORLD"
string.split(separator)	Returns an array of strings containing the substrings of `string` that are separated by `separator`. See also the array method `join`. Examples: "`first name,last name,age".split(",")` -> an array `a` such that `.length` is 3, `a[0]` is `"first name"`, `a[1]` is `"last name"`, and `a[2]` is `"age"`. If `string` does not contain `separator`, an array with one element containing the whole string is returned. Example: `"hello".split(",")` –> an array a such that a.length is 1 and a[0] is "hello",
string.toString()	Returns the string itself.