how do fix the "Cannot GET /submit"?

<form action="submit">
    <input for="input" type="text" />
    <button class="signup">Sign Up</button>
</form>

var input = document.getElementById("input") var length = document.getElementById("length")

function submit(input) {

if (input.value.length <= 6) {
    console.log(hi);
    return false;
} else if (input.length >= 6) {
    console.log("true");
    return true;
}

}