pkring

<input type="button" id="button1" value="В начало" onclick="push1()">
	<input type="button" id="button2" value="В конец" onclick="push2()"><br><br>
	<input type="text" id="text" placeholder="Добавьте текст" onkeyup="pressAfterText()">
	<p id="array"></p>

function pressAfterText(e) {
	e = e || window.event;
	if (e.keyCode === 13) {
		document.getElementById("button1").click();
		document.getElementById("button2").click();
	}
	return false;
}

var element = document.getElementById('array'),
	text = document.getElementById('text'),
	textValue = text.value;


var arr = ["Apple", "Samsung", "Huawei"];

element.textContent = arr;

function push1() {
	textValue = text.value;
	arr.unshift(textValue);
	element.textContent = arr.join();
	console.log(arr);
}

function push2() {
	textValue = text.value;
	arr.push(textValue);
	element.textContent = arr.join();
}