How to Use charCodeAt in JavaScript: Syntax and Examples

Use the charCodeAt(index) method on a string to get the Unicode number of the character at the given index. The index starts at 0 for the first character. If the index is out of range, it returns NaN.

Syntax

The charCodeAt() method is called on a string and takes one argument:

• index: The position of the character in the string (starting from 0).

It returns a number representing the UTF-16 code unit of the character at that position.

javascript

string.charCodeAt(index)

Example

This example shows how to get the Unicode code of the first character in a string and the third character.

javascript

const text = 'Hello';
const firstCharCode = text.charCodeAt(0); // 'H'
const thirdCharCode = text.charCodeAt(2); // 'l'
console.log(firstCharCode);
console.log(thirdCharCode);

Output

72
108

Common Pitfalls

• Using an index that is negative or greater than or equal to the string length returns NaN.
• Remember that charCodeAt() returns a number, not the character itself.
• For characters outside the Basic Multilingual Plane (like some emojis), charCodeAt() returns the code of the first part of the surrogate pair, which may be confusing.

javascript

const str = 'Hi';
console.log(str.charCodeAt(5)); // NaN because index 5 is out of range

// Correct usage:
console.log(str.charCodeAt(1)); // 105 (Unicode for 'i')

Output

NaN
105

Quick Reference

Method	Description	Example	Output
charCodeAt(index)	Returns UTF-16 code unit of character at index	'A'.charCodeAt(0)	65
charCodeAt(index)	Returns NaN if index out of range	'A'.charCodeAt(5)	NaN

Key Takeaways

Use charCodeAt(index) to get the Unicode number of a character at a specific position in a string.

Index starts at 0; out-of-range indexes return NaN.

charCodeAt returns a number, not the character itself.

For some special characters like emojis, charCodeAt may return part of a surrogate pair.