JavaScript Array lastIndexOf()Method

Array 对象参考手册JavaScript Array Object

Example

Find the position of the array element "Apple":

var fruits = ["Banana", "Orange", "Apple", "Mango"];
var a = fruits.lastIndexOf("Apple");

aOutput:

2

The output of the above example means that "Apple" is located at the 2nd position in the array.

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Definition and Usage

The lastIndexOf() method returns the position of the last occurrence of a specified element in an array, searching backward from the end of the string.

If the element to be searched does not appear, the method returns -1.

This method searches the array for the specified element item from tail to head. The search starts at the start position in the array, or at the end of the array (when no start parameter is specified). If an item is found, it returns the position of the first occurrence of item when searching from tail to front. Array indexes start at 0.

If the specified element is not found in the array, it returns -1.

Tip:If you want to find the first occurrence position in an array, please use theindexOf() method。

Browser Support

Internet ExplorerFirefoxOperaGoogle ChromeSafari

All major browsers support the lastIndexOf() property, but Internet Explorer 8 and earlier IE versions do not support this method.

Syntax

array.lastIndexOf(item,start)

Parameter Values

Parameter Description
item Required. Specifies the string value to be searched.
start Optional integer parameter. Specifies the position in the string to start the search. Its valid values are 0 to stringObject.length - 1. If this parameter is omitted, the search will start from the last character of the string.

Return Value

Type Description
Number If searchvalue exists before the fromindex position in stringObject, the position of the last occurrence of searchvalue is returned.

Technical Details

JavaScript Version: 1.6

More Examples

Example

Find the position of "Apple" in the array:

var fruits=["Banana","Orange","Apple","Mango","Banana","Orange","Apple"];
var a = fruits.lastIndexOf("Apple");

aOutput:

6

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Example

Find the position where the string "Apple" appears starting from the fourth position in the array:

var fruits=["Banana","Orange","Apple","Mango","Banana","Orange","Apple"];
var a = fruits.lastIndexOf("Apple",4);

aResult output:

2

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Array 对象参考手册JavaScript Array Object

Other Extensions