Description:
Javascript array
lastIndexOf() method returns the last index
at which a given element can be found in the array, or -1 if it is not
present. The array is searched backwards, starting at
fromIndex.
Syntax:
array.lastIndexOf(searchElement[, fromIndex]);
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Here is the detail of parameters:
- searchElement : Element to locate in the array.
- fromIndex : The index at which to start searching
backwards. Defaults to the array's length, i.e. the whole array will be
searched. If the index is greater than or equal to the length of the
array, the whole array will be searched. If negative, it is taken as the
offset from the end of the array.
Return Value:
Returns index of the found element from the last.
Compatibility:
This method is a JavaScript extension to the ECMA-262 standard; as
such it may not be present in other implementations of the standard. To
make it work you need to add following code at the top of your script:
if (!Array.prototype.lastIndexOf)
{
Array.prototype.lastIndexOf = function(elt /*, from*/)
{
var len = this.length;
var from = Number(arguments[1]);
if (isNaN(from))
{
from = len - 1;
}
else
{
from = (from < 0)
? Math.ceil(from)
: Math.floor(from);
if (from < 0)
from += len;
else if (from >= len)
from = len - 1;
}
for (; from > -1; from--)
{
if (from in this &&
this[from] === elt)
return from;
}
return -1;
};
}
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Example:
<html>
<head>
<title>JavaScript Array lastIndexOf Method</title>
</head>
<body>
<script type="text/javascript">
if (!Array.prototype.lastIndexOf)
{
Array.prototype.lastIndexOf = function(elt /*, from*/)
{
var len = this.length;
var from = Number(arguments[1]);
if (isNaN(from))
{
from = len - 1;
}
else
{
from = (from < 0)
? Math.ceil(from)
: Math.floor(from);
if (from < 0)
from += len;
else if (from >= len)
from = len - 1;
}
for (; from > -1; from--)
{
if (from in this &&
this[from] === elt)
return from;
}
return -1;
};
}
var index = [12, 5, 8, 130, 44].lastIndexOf(8);
document.write("index is : " + index );
var index = [12, 5, 8, 130, 44, 5].lastIndexOf(5);
document.write("<br />index is : " + index );
</script>
</body>
</html>
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This will produce following result:
index is : 2
index is : 5
+JavaScript +JavaScript Frameworks Links +Javascript Development
+JavaScript's and More, Software and Marketing +JavascriptU +JavaScriptOn
+Javascript Problems +JavaScriptOn
+javaScript is a creek in West Virginia in the summe
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