Define unescape() and escape() functions?

In JavaScript, the escape() and unescape() functions were used historically to encode and decode strings for URL purposes. However, these functions have been deprecated in favor of more robust methods like encodeURIComponent() and decodeURIComponent().

escape() Function

The escape() function was used to encode a string by replacing non-ASCII and special characters with their hexadecimal Unicode escape sequences.

var originalString = "Hello, this is a test!"; var escapedString = escape(originalString); console.log(escapedString); // Output: "Hello%2C%20this%20is%20a%20test%21"

In this example, spaces were encoded as %20, and the exclamation mark was encoded as %21.

unescape() Function

The unescape() function was used to decode a string encoded with the escape() function, converting hexadecimal escape sequences back to their original characters.

var escapedString = "Hello%2C%20this%20is%20a%20test%21"; var originalString = unescape(escapedString); console.log(originalString); // Output: "Hello, this is a test!"

However, both escape() and unescape() have issues with encoding and decoding certain characters, and they don't provide adequate protection against URL manipulation attacks. As a result, they are considered obsolete and should be avoided.

Modern JavaScript

Instead, modern JavaScript recommends using the encodeURIComponent() and decodeURIComponent() functions for URL encoding and decoding:

var originalString = "Hello, this is a test!"; var encodedString = encodeURIComponent(originalString); console.log(encodedString); // Output: "Hello%2C%20this%20is%20a%20test%21" var decodedString = decodeURIComponent(encodedString); console.log(decodedString); // Output: "Hello, this is a test!"

The encodeURIComponent() function ensures that the resulting encoded string is safe for inclusion in a URL, addressing some of the vulnerabilities of the old escape() function. Similarly, decodeURIComponent() decodes a URL-encoded string back to its original form. These functions provide better support for international characters and are recommended for modern web development.

Conclusion

The escape() and unescape() functions in JavaScript were once used to encode and decode strings for URL purposes by replacing non-ASCII and special characters with hexadecimal Unicode escape sequences. However, due to their limitations and security vulnerabilities, they have been deprecated in favor of the safer and more versatile encodeURIComponent() and decodeURIComponent() functions for proper URL encoding and decoding.






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