# E0287: upper case letters compared with toLowerCase

Comparing the result of a function named `toLowerCase` to a string literal with one or more upper case letters will always yield the same result.

    let x = "BaNaNa";

    // always returns 'false'
    if (x.toLowerCase() === "BANANA") {
    }

    // always returns 'true'
    if (x.toLowerCase() !== "BANANA") {
    }

Introduced in quick-lint-js version 2.9.0.

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