How to Encode Unicode Characters

Problem

You need to represent non-ASCII Unicode characters (like emoji or CJK characters) in systems that only accept ASCII.

Prerequisites

• Understanding of Unicode code points
• Familiarity with UTF-8 encoding

Steps

1. 1. Find the code point

   Look up the Unicode code point of your character. For example, the euro sign € is U+20AC. The code point is a scalar value that uniquely identifies the character in the Unicode standard.

   Input

   €

   Output

   U+20AC

2. 2. Convert to the target representation

   For JavaScript strings, use \u20AC or \u{20AC}. For UTF-8 bytes, encode as 0xE2 0x82 0xAC. For HTML, use € or €. Choose the representation your target system expects.

   Input

   €

   Output

   JS: \u20AC | UTF-8: E2 82 AC | HTML: €

3. 3. Verify round-trip fidelity

   Decode the representation back to the original character and compare. Characters outside the Basic Multilingual Plane (above U+FFFF) require surrogate pairs in UTF-16, so pay extra attention to emoji and rare scripts.

   Input

   \u20AC

   Output

   €

Expected result

A correct ASCII-safe representation of the Unicode character that decodes back to the exact original.

Common errors

Using \uXXXX for characters above U+FFFF without surrogate pairs

Use the \u{XXXXX} brace syntax in JavaScript or compute the surrogate pair manually for older environments.

Confusing UTF-8 byte count with code point value

UTF-8 uses 1-4 bytes per character. The byte values are not the same as the code point. Use a proper encoder.

Troubleshooting

• If a character shows as two boxes, it was split into surrogate pairs incorrectly. Use a UTF-8-aware tool.
• Check that your file editor saves as UTF-8 without BOM to avoid hidden bytes.

Security limits

• Unicode encoding does not sanitize input. Be aware of homoglyph attacks where visually identical characters from different scripts are used to deceive.