var stack var head -1 function isEmpty return head -1 function push if

var stack = [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0];
var head = -1;

function isEmpty() {
	return head == -1;
}

function push(x) {
	if (head + 1 >= stack.length) {
		console.log("Stack overflow");
		return;
	}
	stack[head++] = x;
}

function pop(x) {
	if (!isEmpty()) {
		return stack[head--];
	}
	console.log("EmptyStack");
}