Disable buttons using javascript (no jquery)

This code uses document.querySelectorAll. It will not work in newer browsers. This is for so question: http://stackoverflow.com/questions/32601264/disable-all-buttons-on-click-of-any-of-the-button

HTML

<form>
    <input name="meleeattack" type="submit" class="fightaction2" value="Melee Attack">
<input name="magicattack" type="submit" class="fightaction2" value="Magic Attack">
<input name="runaway" type="submit" class="fightaction2" value="Forfeit">
<input name="healthpotion" type="submit" class="fightaction2" value="Use HP Potion">
</form>

JavaScript

var input = document.querySelectorAll('input');


[].forEach.call(input, function (btn) {
    btn.addEventListener("click", function (e) {
        e.preventDefault();
        disableAllInputs();
        return false;
    });
});

function disableAllInputs(){
    [].forEach.call(input, function (btn) {
        btn.disabled=true;
    });
}