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    String.prototype.lastIndexOf()

    Summary

    The lastIndexOf() method 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.

    Syntax

    str.lastIndexOf(searchValue[, fromIndex])

    Parameters

    searchValue
    A string representing the value to search for.
    fromIndex
    Optional. The location within the calling string to start the search at, indexed from left to right. It can be any integer. The default value is str.length. If it is negative, it is treated as 0. If fromIndex > str.length, fromIndex is treated as str.length.

    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
    

    Case-sensitivity

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

    'Blue Whale, Killer Whale'.lastIndexOf('blue'); // returns -1
    

    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';
    
    console.log('The index of the first w from the beginning is ' + anyString.indexOf('w'));
    // Displays 8
    console.log('The index of the first w from the end is ' + anyString.lastIndexOf('w')); 
    // Displays 10
    
    console.log('The index of "new" from the beginning is ' + anyString.indexOf('new'));
    // Displays 6
    console.log('The index of "new" from the end is ' + anyString.lastIndexOf('new'));
    // Displays 6
    

    Specifications

    Specification Status Comment
    ECMAScript 1st Edition. Standard Initial definition.
    ECMAScript 5.1 (ECMA-262)
    The definition of 'String.prototype.lastIndexOf' in that specification.
    Standard  
    ECMAScript 6 (ECMA-262)
    The definition of 'String.prototype.lastIndexOf' in that specification.
    Draft  

    Browser compatibility

    Feature Chrome Firefox (Gecko) Internet Explorer Opera Safari
    Basic support (Yes) (Yes) (Yes) (Yes) (Yes)
    Feature Android Chrome for Android Firefox Mobile (Gecko) IE Mobile Opera Mobile Safari Mobile
    Basic support (Yes) (Yes) (Yes) (Yes) (Yes) (Yes)

    See also

    Document Tags and Contributors

    Last updated by: Mingun,
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