JavaScript - inhabilitar botón después de pulsarlo

$("input").attr('disabled','disabled')

$("input").removeAttr('disabled','disabled')

<script>

var p=null;

function test(e) {

if (p != null) p.disabled=false;

p=e;

e.disabled=true;

}

</script>

<input type="button" onfocus="test(this)" value="Botón #1">

<input type="button" onfocus="test(this)" value="Botón #2">

<input type="button" onfocus="test(this)" value="Botón #3">

<input type="button" onfocus="test(this)" value="Botón #4">

<a href="#top" onClick="carga01()"><img src="../jpg/koryo.jpg">

</a>

function carga01() {

 // document.getElementById("tituloVideo").innerHTML = 'TITULO VIDEO DOS';

  document.getElementById("subTVideo").innerHTML = 'POOMSAE KORYO';

  document.getElementById("mp4_src").src = "../videos/koryo.mp4";

  document.getElementById("myVideo").load();

}

<script>

var p=null;

function test(e) {

if (p != null) p.disabled=false;

p=e;

e.disabled=true;

}

</script>

<input type="image" src="img1.jpg" width="48" height="48" onfocus="test(this)" value="Botón #1">

<input type="image" src="img2.jpg" width="48" height="48" onfocus="test(this)" value="Botón #2">

<input type="image" src="img3.jpg" width="48" height="48" onfocus="test(this)" value="Botón #3">

<input type="image" src="img4.jpg" width="48" height="48" onfocus="test(this)" value="Botón #4">