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Revision 62471 of String.prototype.lastIndexOf()

  • Revision slug: JavaScript/Reference/Global_Objects/String/lastIndexOf
  • Revision title: lastIndexOf
  • Revision id: 62471
  • Created:
  • Creator: Anonymous
  • Is current revision? No
  • Comment /* Description */

Revision Content

Summary

Returns the index within the calling String object of the last occurrence of the specified value, or -1 if not found. The calling string is searched backward, starting at fromIndex.

Method of String
Implemented in: JavaScript 1.0, NES2.0
ECMA Version: ECMA-262

Syntax

lastIndexOf(searchValue{{mediawiki.external(', <i>fromIndex</i>')}})

Parameters

searchValue 
A string representing the value to search for.
fromIndex 
The location within the calling string to start the search from. It can be any integer between 0 and the length of the string. The default value is the length of the string.

Description

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

"canal".lastIndexOf("a")   // returns 3
"canal".lastIndexOf("a",2) // returns 1
"canal".lastIndexOf("a",0) // returns -1
"canal".lastIndexOf("x")   // returns -1

The lastIndexOf method is case sensitive. For example, the following expression returns -1:

"Blue Whale, Killer Whale".lastIndexOf("blue") 

Examples

Example: Using indexOf and lastIndexOf

The following example uses indexOf and lastIndexOf to locate values in the string "Brave new world".

var anyString="Brave new world"

// Displays 8
document.write("<P>The index of the first w from the beginning is " +
   anyString.indexOf("w"))
// Displays 10
document.write("<P>The index of the first w from the end is " +
   anyString.lastIndexOf("w"))
// Displays 6
document.write("<P>The index of 'new' from the beginning is " +
   anyString.indexOf("new"))
// Displays 6
document.write("<P>The index of 'new' from the end is " +
   anyString.lastIndexOf("new"))

See Also

charAt, indexOf, split

Revision Source

<p>
</p>
<h3 name="Summary"> Summary </h3>
<p>Returns the index within the calling <code>String</code> object of the last occurrence of the specified value, or -1 if not found. The calling string is searched backward, starting at <code>fromIndex</code>.
</p>
<table class="fullwidth-table">
<tbody><tr>
<td class="header" colspan="2">Method of <a href="en/Core_JavaScript_1.5_Reference/Objects/String">String</a></td>
</tr>
<tr>
<td>Implemented in:</td>
<td>JavaScript 1.0, NES2.0</td>
</tr>
<tr>
<td>ECMA Version:</td>
<td>ECMA-262</td>
</tr>
</tbody></table>
<h3 name="Syntax"> Syntax </h3>
<p><code>
lastIndexOf(<i>searchValue</i>{{mediawiki.external(', &lt;i&gt;fromIndex&lt;/i&gt;')}})
</code>
</p>
<h3 name="Parameters"> Parameters </h3>
<dl><dt> <code>searchValue</code> </dt><dd> A string representing the value to search for.  
</dd></dl>
<dl><dt> <code>fromIndex</code> </dt><dd> The location within the calling string to start the search from. It can be any integer between 0 and the length of the string. The default value is the length of the string.
</dd></dl>
<h3 name="Description"> Description </h3>
<p>Characters in a string are indexed from left to right. The index of the first character is 0, and the index of the last character is <code>stringName.length - 1</code>.
</p>
<pre>"canal".lastIndexOf("a")   // returns 3
"canal".lastIndexOf("a",2) // returns 1
"canal".lastIndexOf("a",0) // returns -1
"canal".lastIndexOf("x")   // returns -1
</pre>
<p>The <code>lastIndexOf</code> method is case sensitive. For example, the following expression returns -1:
</p>
<pre>"Blue Whale, Killer Whale".lastIndexOf("blue") 
</pre>
<h3 name="Examples"> Examples </h3>
<h4 name="Example:_Using_indexOf_and_lastIndexOf"> Example: Using <code>indexOf</code> and <code>lastIndexOf</code> </h4>
<p>The following example uses <code>indexOf</code> and <code>lastIndexOf</code> to locate values in the string "<code>Brave new world</code>".
</p>
<pre>var anyString="Brave new world"

// Displays 8
document.write("&lt;P&gt;The index of the first w from the beginning is " +
   anyString.indexOf("w"))
// Displays 10
document.write("&lt;P&gt;The index of the first w from the end is " +
   anyString.lastIndexOf("w"))
// Displays 6
document.write("&lt;P&gt;The index of 'new' from the beginning is " +
   anyString.indexOf("new"))
// Displays 6
document.write("&lt;P&gt;The index of 'new' from the end is " +
   anyString.lastIndexOf("new"))
</pre>
<h3 name="See_Also"> See Also </h3>
<p><a href="en/Core_JavaScript_1.5_Reference/Objects/String/charAt">charAt</a>,
<a href="en/Core_JavaScript_1.5_Reference/Objects/String/indexOf">indexOf</a>,
<a href="en/Core_JavaScript_1.5_Reference/Objects/String/split">split</a>
</p>
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