24.161. String: support for strings ECMAScript v1: Object  String 24.161.1. Constructor new String(s) // Constructor function String(s) // Conversion function
24.161.1.1. Arguments
s The value to be stored in a String object or converted to a primitive string. 24.161.1.2. Returns When String( ) is used as a constructor with the new operator, it returns a String object, which holds the string s or the string representation of s. When the String( ) constructor is used without the new operator, it simply converts s to a primitive string and returns the converted value. 24.161.2. Properties
length The number of characters in the string. 24.161.3. Methods
charAt( ) Extracts the character at a given position from a string.
charCodeAt( ) Returns the encoding of the character at a given position in a string.
concat( ) Concatenates one or more values to a string.
indexOf( ) Searches the string for a character or substring.
lastIndexOf( ) Searches the string backward for a character or substring.
localeCompare( ) Compares strings using locale-specific ordering.
match( ) Performs pattern matching with a regular expression.
replace( ) Performs a search-and-replace operation with a regular expression.
search( ) Searches a string for a substring that matches a regular expression.
slice( ) Returns a slice or substring of a string.
split( ) Splits a string into an array of strings, breaking at a specified delimiter string or regular expression.
substr( ) Extracts a substring of a string; a variant of substring( ).
substring( ) Extracts a substring of a string.
toLowerCase( ) Returns a copy of the string, with all characters converted to lowercase.
toString( ) Returns the primitive string value.
toUpperCase( ) Returns a copy of the string, with all characters converted to uppercase.
valueOf( ) Returns the primitive string value. 24.161.4. Static Methods
String.fromCharCode( ) Creates a new string using the character codes passed as arguments. 24.161.5. HTML Methods Since the earliest days of JavaScript, the String class has defined a number of methods that return a string modified by placing it within HTML tags. These methods have never been standardized by ECMAScript but can be useful in both client- and server-side JavaScript code that dynamically generates HTML. If you are willing to use nonstandard methods, you might create the HTML source for a bold, red hyperlink with code like this: var s = "click here!"; var html = s.bold( ).link("javascript:alert('hello')").fontcolor("red");
Because these methods are not standardized, they do not have individual reference entries in the pages that follow:
anchor( name) Returns a copy of the string, in an <a name=> environment.
big( ) Returns a copy of the string, in a <big> environment.
blink( ) Returns a copy of the string, in a <blink> environment.
bold( ) Returns a copy of the string, in a <b> environment.
fixed( ) Returns a copy of the string, in a <tt> environment.
fontcolor( color) Returns a copy of the string, in a <font color=> environment.
fontsize( size) Returns a copy of the string, in a <font size=> environment.
italics( ) Returns a copy of the string, in an <i> environment.
link( url) Returns a copy of the string, in an <a href=> environment.
small( ) Returns a copy of the string, in a <small> environment.
strike( ) Returns a copy of the string, in a <strike> environment.
sub( ) Returns a copy of the string, in a <sub>
sup( ) Returns a copy of the string, in a <sup> environment. 24.161.6. Description Strings are a primitive datatype in JavaScript. The String class type exists to provide methods for operating on primitive string values. The length property of a String object specifies the number of characters in the string. The String class defines a number of methods for operating on strings; for example, there are methods for extracting a character or a substring from the string or searching for a character or a substring. Note that JavaScript strings are immutable: none of the methods defined by the String class allows you to change the contents of a string. Instead, methods such as String.toUpperCase( ) return an entirely new string, without modifying the original. In implementations of JavaScript derived from the original Netscape code base (such as the implementation in Firefox), strings behave like read-only arrays of characters. For example, to extract the third character from a string s, you can write s[2] instead of the more standard s.charAt(2). In addition, when the for/in statement is applied to a string, it enumerates these array indexes for each character in the string. (Note, however, that the length property is not enumerated, as per the ECMAScript specification.) Because this string-as-array behavior is not standard, you should avoid using it. 24.161.7. See Also Chapter 3 |
