JavaScript Array method: lastIndexOf()
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The lastIndexOf() method (when applied to a
JavaScript
array) returns
the index of the first element of an array found when an array is searched,
backwards from the end.
It
has the following syntax with the following parameters. It returns a number
as above (or -1 if no array element passes the test).
array.lastIndexOf(item, start)
|
Parameter
|
Required / Optional
|
Description
|
|
item
|
Required
|
Item to search for
|
|
start
|
Optional
|
Index value at which to
start search. Negative values indicate start from a position counting from
the beginning and then search backwards to the start
|
EXAMPLE:
HTML USED IN THIS EXAMPLE:
<!DOCTYPE html>
<html> <!-- Copyright (c) Nematrian Limited 2018 -->
<head>
<style>
table,th,tr,td {border: 1px solid black; border-collapse: collapse;}
</style>
</head>
<body>
<table>
<tr>
<th>Example</th>
<th>Resulting value of <code>x</code></th>
</tr>
<tr>
<td><code id="Example"></code></td>
<td><code id="Result"></code></td>
</tr>
</table>
<script>
var h = ["a","b","b"];
document.getElementById("Example").innerHTML =
'var h = ["a","b","b"];<br>' +
'var x = h.lastIndexOf("b");';
document.getElementById("Result").innerHTML
= h.lastIndexOf("b");
</script>
</body>
</html>
|
FUNCTION THAT MAY ASSIST IN TESTING WHETHER FEATURE IS SUPPORTED:
function isSupportedJavaScriptMethodArrayLastIndexOf() {
var h = [1, 2, 3]; return !!h.lastIndexOf;
} |
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