charAtComparisons

Reports comparing charAt() results with strings longer than one character.

✅ This rule is included in the ts logical presets.

The charAt method returns a string of exactly one character. If the return value is compared with a string of length greater than one, the comparison will always evaluate to the same result. Equality comparisons (===, ==) will always be false, and inequality comparisons (!==, !=) will always be true.

Examples

❌ Incorrect

text.charAt(0) === "ab";

"abc" === text.charAt(0);

text.charAt(0) !== "hello";

✅ Correct

text.charAt(0) === "a";

text.slice(0, 2) === "ab";

text.startsWith("ab");

Options

This rule is not configurable.

When Not To Use It

This rule catches a specific programming error with no legitimate use cases. There is no reason to disable this rule.

Further Reading

• MDN documentation on String.prototype.charAt()

Equivalents in Other Linters

• Oxlint: oxc/bad-char-at-comparison