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Java Script Character Encoding and Decoding

By Stephen Bucaro

You may have already discovered that the address bar in your web browser won't accept a character string with a space in it. To get the character string to work, you need to replace the space with something. That something is the hexadecimal code for a space %20.

In addition to not accepting spaces, other characters have meaning in a URL (Uniform Resource Locator). For example a question mark needs to be replaced with %3F, an ampersand needs to be replaced with %26, and an equal sign needs to be replaced with %3D.

Fortunately, you don't have to perform these replacements manually, Java Script provides several functions that will automatically replace the necessary characters in a string with their hexadecimal code equivalents. The Java Script escape function returns a string with all spaces and non-alphanumeric characters replaced with their hexadecimal code equivalents.

Click on the link below to see an example.

escape('!@#$%^&*(){}[]=:;?+./')

The escape function was designed for URLs (addresses to web resources). The W3C now views the Web as a set of named objects accessed by URIs (Uniform Resource Identifier). Some object names use characters that are escaped by the escape function, so in Java Script 1.5 (ECMAScript 3.0) and higher, the escape function has been deprecated in favor of the encodeURI function.

Java Script 1.5 also provides the encodeURIComponent function, which can be used to encode part of a URI. For example, if you created an identifier containing a slash, neither the escape function nor the encodeURI will encode slashes because they are a legal characters in a URL or URI.

You could encode it with the encodeURIComponent function, But you wouldn't use the encodeURIComponent function to encode an entire URI because it would replace the directory delimiter slashes with their hexadecimal code equivalents.

Which to use; encodeURI, encodeURIComponent, or escape?

escape does not encode these characters: @*/+. Since the + and . characters have meaning in a URI, escape is not useful for encoding URIs. encodeURI does not encode these characters: !@#$&*()=:/;?+' Since the & + and ? characters are used in query strings, encodeURI is not useful for encoding URLs.

Click on the link below to see an example.

encodeURI('!@#$%^&*(){}[]=:;?+./')