JavaScript - Auto Click en un botón tipo submit sin ID

<form>

	<button value="Valor" name="Enviar">Enviar</button>

</form>

<script>

	document.querySelector('button[name=Enviar]').addEventListener('click',function(e){

		e.preventDefault();

		console.log('Enviado');

	});

	setInterval(function(){

		document.querySelector('button[name=Enviar]').click();

	},5000);

</script>

<button class="ab" onmouseover="myFunction()" onclick="alert('click event occured')">Start a chat</button>

<script>

function myFunction() {

 document.querySelector('button[class=ab]').click()

}

</script>

document.querySelector('button[class=a b]').click()

console.log(document.querySelector('button[class="a b"]'));

document.querySelector('button[class=a.b]').click()

while(true) {setTimeout(function(){ document.getElementsByClassName('classdelbotonaqui').click(); }, 10000);}