EdemKakMozhem,
с циклом
<!DOCTYPE html>
<html>
<head>
<title>Untitled</title>
<meta charset="utf-8">
<script>
document.addEventListener("DOMContentLoaded", function() {
let form = document.querySelector(".form");
let btn = document.querySelector(".btn-next");
btn.setAttribute("disabled", true);
let radioBtn = document.querySelectorAll('input[type="radio"]');
radioBtn.forEach(function(input) {
input.addEventListener("change", function() {
btn.removeAttribute("disabled");
})
})
})
</script>
</head>
<body>
<form class="form">
<input class="radio" id="block-11m" type="radio" name="radio" value="level-2">
<label for="block-11m">одноэтажный</label>
<input class="radio" id="block-12m" type="radio" name="radio" value="leveд-1">
<label for="block-12m">двухэтажный</label>
<input class="radio" id="block-13m" type="radio" name="radio" value="level-3">
<label for="block-13m">трехэтажный</label>
<button class="btn-next" name="submit" type="submit">ДАЛЕЕ</button>
</form>
</body>
</html>
с делегированием
<!DOCTYPE html>
<html>
<head>
<title>Untitled</title>
<meta charset="utf-8">
<script>
document.addEventListener("DOMContentLoaded", function() {
let form = document.querySelector(".form");
let btn = document.querySelector(".btn-next");
btn.setAttribute("disabled", true);
form.addEventListener("change", function({
target
}) {
if (target.closest('.radio')) this.submit.disabled = false;
})
})
</script>
</head>
<body>
<form class="form">
<input class="radio" id="block-11m" type="radio" name="radio" value="level-2">
<label for="block-11m">одноэтажный</label>
<input class="radio" id="block-12m" type="radio" name="radio" value="leveд-1">
<label for="block-12m">двухэтажный</label>
<input class="radio" id="block-13m" type="radio" name="radio" value="level-3">
<label for="block-13m">трехэтажный</label>
<button class="btn-next" name="submit" type="submit">ДАЛЕЕ</button>
</form>
</body>
</html>