JavaScript String Object
The Most Common Methods
NN: Netscape, IE: Internet Explorer, ECMA: Web Standard
| Methods |
Explanation |
NN |
IE |
ECMA |
| length |
Returns the number of characters in a string |
2.0 |
3.0 |
1.0 |
| indexOf() |
Returns the index of the first time the specified character
occurs, or -1 if it never occurs, so with that index you can determine if the string contains the specified character. |
2.0 |
3.0 |
|
| lastIndexOf() |
Same as indexOf, only it starts from the right and moves left. |
2.0 |
4.0 |
|
| match() |
Behaves similar to indexOf and lastIndexOf, but the match
method returns the specified characters, or "null", instead of a
numeric value. |
4.0 |
4.0 |
|
| substr() |
Returns the characters you specified: (14,7) returns 7
characters, from the 14th character. |
4.0 |
4.0 |
|
| substring() |
Returns the characters you specified: (7,14) returns all
characters between the 7th and the 14th. |
2.0 |
3.0 |
1.0 |
| toLowerCase() |
Converts a string to lower case |
2.0 |
3.0 |
1.0 |
| toUpperCase() |
Converts a string to upper case |
2.0 |
3.0 |
1.0 |
Examples
The length method
The length method returns the number of characters in a string.
<html>
<body>
<script type="text/javascript">
var str="Web Enabling Tools is Cool!"
document.write("<p>" + str + "</p>")
document.write("str.length")
</script>
</body>
</html>
|
The indexOf() method
Test if a string contains a specified character. Returns an integer if it does
and -1 if it does not. Use this method in a form
validation.
<html>
<body>
<script type="text/javascript">
var str="Web Enabling Tools is Cool!"
var pos=str.IndexOf("Enabling")
if (pos>=0)
{
document.write("School found at position: ")
document.write(pos + "<br>")
} else {
document.write("Enabling not found!")
}
<p>This example tests if a string contains a specified word.
If the word is found it returns the position of the first character
of the word in the original string. Note: The first position in the
string is 0!
</script>
</body>
</html>
|
The match() method
Works similar to the indexOf method, only this method returns the characters you
specified, "null" if the string does not contain the specified
characters.
<html>
<body>
<script type="text/javascript">
var str="Web Enabling Tools is cool!"
document.write(str.match("cool"))
</script>
<p>This example tests if a string contains a specified word.
If the word is found it returns the word!
</body>
</html>
|
The substr() method
Returns a specified part of a string. If you specify (3,6) the returned result string will be from the
third character and 6 long. (Note that since the first
character is 0, the second is 1 etc, the result will be from the second
character and 6 long).
<html>
<body>
<script type="text/javascript">
var str="W3Schools is great!"
document.write(str.substr(2,6))
document.write("<br><br>")
document.write(str.substring(2,6))
</script>
<p>The substr() method returns a specified part of a string. If you specify (2,6) the returned string will be from the second character (start at 0) and 6 long.
<p>The substring() method also returns a specified part of a string. If you specify (2,6) it returns all characters from the second character (start at 0) and up to, but not including, the sixth character.
</body>
</html>
|
The substring() method
Returns a specified part of a string. (3,6) returns the characters from the third to the 6th.
<html>
<body>
<script type="text/javascript">
var str="W3Schools is great!"
document.write(str.substring(3,6))
</script>
<p>This example returns all the characters from the third character up to but not including the 6th character. (Note that since the first character is 0, the second is 1 etc, the result will be from the fourth character including the 6th character).
</body>
</html>
|
The toLowerCase() and toUpperCase()
methods
Converts a string to lower case and upper case respectively.
<html>
<body>
<script type="text/javascript">
var str=("Hello JavaScripters!")
document.write(str.toLowerCase())
document.write("<br>")
document.write(str.toUpperCase())
</script>
</body>
</html>
|
|