JavaScript | typedArray.lastIndexOf() with Examples

Last Updated : 03 Aug, 2018

The typedArray.lastIndexOf() is an inbuilt function in JavaScript which is used to return the last index of the typedArray at which a given element is present otherwise it returns -1 if the element is not present.
Syntax:

typedArray.lastIndexOf(search_Element, from_Index])

Parameters: It accept two parameters which are specified below:

search_Element: It is the element whose last index is to be searched.
from_Index: It is optional. It is the index upto which an element is to be searched and its default value is the length of the typedArray.

Return value: It returns the last index of the typedArray at which a given element is present otherwise it returns -1 if the element is not present.

JavaScript code to show the working of above function:
Code #1:

<script> 
  
  // Creating a typedArray with some elements 
  var A = new Uint8Array([5, 10, 15, 15, 5, 20, 10]); 
    
  // Calling lastIndexOf() function 
  b = A.lastIndexOf(10);      
  c = A.lastIndexOf(5);      
  d = A.lastIndexOf(15);   
  e = A.lastIndexOf();   
  f = A.lastIndexOf(20);  
  g = A.lastIndexOf(25);  
    
  // Printing returned values 
  document.write(b +"<br>"); 
  document.write(c +"<br>"); 
  document.write(d +"<br>"); 
  document.write(e +"<br>"); 
  document.write(f +"<br>"); 
  document.write(g +"<br>"); 
    
</script> 

Output:

Code #2:

<script> 
  
  // Creating a typedArray with some elements 
  var A = new Uint8Array([5, 10, 15, 15, 5, 20, 10]); 
    
  // Calling lastIndexOf() function 
  b = A.lastIndexOf(10, 1);      
  c = A.lastIndexOf(5, 2);      
  d = A.lastIndexOf(15, 3);   
  e = A.lastIndexOf(15, 1);   
  f = A.lastIndexOf(20, 1);  
  g = A.lastIndexOf(25, 3);  
    
  // Printing returned values 
  document.write(b +"<br>"); 
  document.write(c +"<br>"); 
  document.write(d +"<br>"); 
  document.write(e +"<br>"); 
  document.write(f +"<br>"); 
  document.write(g +"<br>"); 
    
</script> 

Output:

1
0
3
-1
-1
-1

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