HTML - desabilitar formulario

<form id="frm1">

Input 1: <input type="text"><br><br>

Input 2: <input type="text"><br><br>

<input type="submit" value="Enviar">

<input type="reset" value="Borrar">

</form>

<button onclick="test()">Test</button>

<script>

function test() {

var x = document.getElementById("frm1");

for (i = 0; i < x.length ;i++) {

x.elements[i].disabled = true;

}

}

</script>