Strings are commonly used in JavaScript so there are a number of properties and methods provided to manipulate them (properties and methods are covered in the Ojects.Properties.Methods Tutorial).
String Literals
String literals may be enclosed with single or double quotes. Double quote characters may be contained in a single quote string or vice versa.
If variables are required to be written into a string then concatenation must be used as covered in the JavaScript Variables Tutorial.
Escape Sequences
Escape sequences are preceded by the \ character to signify that the characters are to be treated differently.
In a single quoted string if you wish to use the ' character then to avoid JavaScript treating the character as a string delimiter then it must be escaped with the \ character.
The only other escape sequence supported by single quoted strings is the \ character itself, which if used, must be escaped with \.
Single Quotes Escape Sequences
<script language="javascript" type="text/javascript"> document.write ('It\'s a single quote string.');
document.write ('Backslash \\ is used as an escape character.');
</script>
Strings also support a number of escape sequences including...
\t to output a tab character.
\n to output a newline character.
\r to output a carriage return character.
\b to output a backspace character.
Finding the Length of a String
The number of characters in a string can be found from the length property.
Example of the Length Property
<script language="javascript" type="text/javascript">
var name = "George Smith";
var varlen = name.length;
// This prints out 12
document.write(varlen);
</script>
Changing Case
You can change the case of a string with the following methods.
toUpperCase() changes all characters in the string to uppercase.
toLowerCase() changes all characters in the string to lowercase.
Examples of Changing Case
<script language="javascript" type="text/javascript">
var name = "George Smith";
name = name.toUpperCase();
// This prints out GEORGE SMITH
document.write(name);
name = name.toLowerCase();
// This prints out george smith
document.write(name);
</script>
Finding Characters within Strings
The indexOf() method allows you to find the first occurrence of a character or character combination within a string.
The method returns a numeric value with the beginning of the string considered as index zero.
If the character or character combination isn't found then the method returns -1.
Example of indexOf
<script language="javascript" type="text/javascript">
var name = "George Smith";
var position = name.indexOf('m');
// This prints out 8
document.write(position);
</script>
The method also accepts a second argument to allow you to begin the search after an index other than zero and takes the form string.indexOf('m',7).
The lastIndexOf Method
The lastIndexOf() method works in exactly the same way as the indexOf() method but instead of returning the first character, or character combination, it returns the last.
The charAt() Method
This method will return a character at a given position.
Example of indexOf
<script language="javascript" type="text/javascript">
var name = "George Smith";
var char = name.charAt(0);
// This prints out G
document.write(char);
</script>
Extracting Substrings from Strings
JavaScript provides several methods for extracting substrings from strings.
The substring() Method
This method uses two arguments - an index value from the start of the string and a second index value for where to end the substring within the string.
If only the first argument is provided then it will return a substring from the index value to the end of the string.
Example of substring()
<script language="javascript" type="text/javascript">
var name = "George Smith";
var sub = name.substring(0,6);
// This prints out George
document.write(sub);
</script>
The substr() Method
This method works slightly differently to the substring() method. The first argument is the same but the second argument is the length of substring to be extracted.
Example of substr()
<script language="javascript" type="text/javascript">
var name = "George Smith";
var sub = name.substr(7,4);
// This prints out Smit
document.write(sub);
</script>
Replacing Characters within Strings
The replace() method allows you to replace characters, or character combinations, within strings.
The method takes two arguments. The character, or character combination, to be replaced and the character, or character combination to replace it.
Example of replace()
<script language="javascript" type="text/javascript">
var name = "George Smith";
name = name.replace("George","Fred");
// This prints out Fred Smith
document.write(name);
</script>
Free Web Design Tutorials
StringsRegular ExpressionsDefining RegExp PatternsBranches and ConditionsLoopsArraysArray MethodsSorting ArraysUser-Defined FunctionsCookiesWindowsFrames
Previous - The Date Object
Next - Regular Expressions 
