How to use JavaScript lastIndexOf() method

Usage of JavaScript lastIndexOf() method: 1. This method can return the position where a specified string value last appears. If the second parameter start is specified, the specified position in a string will start from the end. Search forward; 2. The lastIndexOf method is case-sensitive.

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JavaScript lastIndexOf() method Usage:

Example

Find the last occurrence position of the string "runoob":

var str="I am from runoob，welcome to runoob site.";
var n=str.lastIndexOf("runoob");

Output result:28

Definition and usage

lastIndexOf() method can return the last occurrence position of a specified string value. If the second parameter start is specified, then Searches a specified position in a string from back to front.

Note: This method will retrieve the string from back to front, but the return is the position of the last occurrence of the substring calculated from the starting position (0). See if it contains a string.

The starting position of the search is at the start of the string or the end of the string (when start is not specified).

If no matching string is found, -1 is returned.

Note: The lastIndexOf() method is case-sensitive!

Tips: You can also refer to the similar method indexOf().

Browser support

Internet, Explorer, Firefox, Opera, GoogleChrome, Safari

All major browsers support the lastIndexOf() method

Syntax

string.lastIndexOf(searchvalue,start)

Parameter value

• searchvalue Required. Specifies the string value to be retrieved.

• start Optional integer parameter. Specifies the position in the string to begin searching. Its legal 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

• #Number The last occurrence position of the searched string, returned if no matching string is found -1.

Technical Details

JavaScript Version: 1.0

More Examples

1. Search for the last occurrence of the string "runoob" starting from the 20th character:

var str="I am from runoob，welcome to runoob site.";
var n=str.lastIndexOf("runoob", 20);

Output result: 10

2. Starting from the 10th character from back to front Find the last occurrence of the string "runoob":

var str="I am from runoob，welcome to runoob site.";
var n=str.lastIndexOf("runoob", 9);

Output result: -1

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