String constructor JS Home  <<  JS Reference  <<  String

String creation.

Description

In JavaScript strings are created using the constructor String or created as string primitives.

  • JavaScript will automatically convert primitives and String objects, so that it's possible to use String object methods for primitive strings:
    • In contexts where a property lookup occurs JavaScript automatically performs the property lookup.
    • In contexts where a method is to be called on a string primitive, JavaScript automatically wraps string primitives and calls the method.

Syntax

Signature Description
var aString = new String(string);Create a String object.
String(string);Create a string primitive.
'stringText'Create a string primitive.
"stringText"Create a string primitive.

Parameters

Parameter Description
stringAny string value.
stringTextAny properly encoded set of characters.

Class Properties

Class Property Description
prototypeEnables property assignment to objects of type String.

Instance Properties

Instance Property Description
constructorReturns a reference to the String function that created the prototype.
lengthA positive integer holding the number of elements within a string.
nA positive integer used to access a character between 0 and length -1.

Class Methods

Class Method Description
fromCharCode()Returns a string created from the specified sequence of Unicode values.

Instance Methods

By using methods of the String object we can access individual characters of strings, split strings into arrays and many other things.

Instance Method Description
Getter (Accessor) MethodsThese methods DO NOT modify the String object or string primitive
charAt()Returns the character at the specified zero based index.
charCodeAt()Returns the Unicode value of the character at the specified zero based index or NaN.
concat()Returns a new string from the concatenation of two or more strings.
indexOf()Returns the index value for the first occurence of the specified string from the specified starting index or -1 if not found.
lastIndexOf()Returns the index value for the last occurence of the specified string from the specified starting index or -1 if not found.
localeCompare()Returns a number dependant on the sort order of string comparison.
match()Returns match(es) of a string and regular expression comparison.
replace()Returns a new string containing some or all of the matches of a replaced pattern.
search()Tries to locate a match between a regular expression and this String object.
slice()Returns an extracted section of a string.
substr()Returns the characters of a section of an existing string.
substring()Returns a part of a string defined by parameters.
toLocaleLowerCase()Returns a copy of a string value converted to lower case, taking into account any specific case mappings for the locale.
toLocaleUpperCase()Returns a copy of a string value converted to upper case, taking into account any specific case mappings for the locale.
toLowerCase()Returns a copy of a string value converted to lower case.
toString()Returns a string representation of an object.
toUpperCase()Returns a copy of a string value converted to upper case.
valueOf()Returns the primitive value of a String object as a string data type.
Setter (Mutator) MethodsThese methods DO modify the String object or string primitive
None.

None.

Usage

Any string primitives have full access to String methods as JavaScript automaticially converts any string primitives to temporary String objects when a String method is called on the string primitive. The following code shows an example of this.



// Create a String object.
aString = new String('happychappy');

alert('aString ' + aString.charAt(4)); // Will show value 'y' in alert box

// Create a string literal and call a String() method on it.
bString = 'happychappy';

alert('aString ' + bString.charAt(4)); // Will show value 'y' in alert box

Press the button below to action the above code:

Related Tutorials

JavaScript Basic Tutorials - Lesson 8 - Strings