JavaScript: decodeURIComponent() vs decodeURI()

Both decodeURI() and decodeURIComponent() are Javascript global functions that are used for decoding encoded URI (Uniform Resource Identifier).

decodeURI() function: It decodes a string previously encoded by encodeURI() function. It returns a decoded URI by replacing each UTF-8 escape sequence with the characters it represents.

  • Syntax:

    decodeURI(encodeURI(x));
  • Parameter It contains single parameter that includes a string previously encoded by encodeURI() function and hence result will be x again.
  • Example: This example using decodeURI() function.
    <!DOCTYPE html> 
    <html> 
    
    <head> 
        <title>decodeURI() Example</title> 
    </head> 
    
    <body> 
        <script type="text/javascript"> 
            var decodeText1 = decodeURI('http://www.testing.com/'); 
            document.write(decodeText1); 
            document.write("<br>"); 
            var decodeText2 = decodeURI('http%3A%2F%2Fwww.testing.com%2F'); 
            document.write(decodeText2); 
        </script> 
    </body> 
    
    </html> 
    
  • Output:
    http://www.testing.com/
    http%3A%2F%2Fwww.testing.com%2F
  • decodeURIComponent() function: It decodes a string previously encoded by encodeURIComponent() function. It returns a decoded URI Component by replacing each UTF-8 escape sequence with the characters it represents. It can decode any value between %00 and %7F.
  • Syntax:

    decodeURIComponent(encodeURIComponent(x));
  • Parameter Single parameter that includes a string previously encoded by encodeURIComponent() and hence result will be x again.
  • Example: This example is on decodeURIComponent()
    <!DOCTYPE html> 
    <html> 
    
    <head> 
        <title>decodeURIComponent() Example</title> 
    </head> 
    
    <body> 
        <script type="text/javascript"> 
            var decodeText1 = decodeURIComponent( 
                            'http://www.testing.com/'); 
            document.write(decodeText1); 
            document.write("<br>"); 
            var decodeText2 = decodeURIComponent( 
                    'http%3A%2F%2Fwww.testing.com%2F'); 
            document.write(decodeText2); 
        </script> 
    </body> 
    
    </html> 
    
  • Output:

    http://www.testing.com/ 
    http://www.testing.com/

Note: Both functions throw URIError indicating that one or more of the escape sequences in string is malformed and cannot be correctly decoded.

Difference between decodeURIComponent() and decodeURI() Function:

    Both can decode alphanumeric characters and – _ . ! ~ * ‘ ( ) characters even but,

  • decodeURI(): It takes encodeURI(url) string so it cannot decoded characters (, / ? : @ & = + $ #)
  • decodeURIComponent(): It takes encodeURIComponent(url) string so it can decode these characters.
  • decodeURI(): It takes encodeURI(url) string as parameter and returns the decoded string.
  • decodeURIComponent(): It takes encodeURIComponent(url) string as parameter and returns the decoded string.
  • decodeURI(“%41”): It returns “A”
  • decodeURIComponent(“%41”) It returns “A”
  • decodeURI(“%26”): It returns “%26”
  • decodeURIComponent(“%26”): It returns “&”