How can get button by tagName without id, class or jQuery?

I want to get button text without id, class or jQuery using tagName and write those text into p tag. My simple test code like below. I hope you understand what I am trying to do.

            <button>Button 1</button>
            <button>Button 2</button>
            <p id="result" ></p>


            <script type="text/javascript">
                function tagName(tag){
                    var buttons = document.getElementsByTagName(tag);
                    var totalButton = buttons.length;

                    for(var i=0;i<totalButton;i++){
                        // here i want to check which button clicked?
                    }

                };

                    tagName("button").onclick = function(){
                    document.getElementById("result").innerHTML = tagName("button").innerHTML;
                }
            </script>

Can you help me for completing this code? Note: I have only one function tagName()

Solution

<html>

<head>
    <script>
        function tagName(tag) {
            var buttons = document.getElementsByTagName(tag);
            var totalButton = buttons.length;

            var r = []
            for (var i = 0; i < totalButton; i++) {
                // here i want to check which button clicked?
                r.push(buttons[i])
            }
            return r;
        };

        function onLoad() {
            tagName("button").forEach(function (item, idx) {
                item.addEventListener('click', function () {
                    document.getElementById("result").innerHTML = item.innerHTML;
                });
            });
        }

    </script>
</head>

<body onload="onLoad()">
    <button>Button 1</button>
    <button>Button 2</button>
    <p id="result"></p>


    <script type="text/javascript">

    </script>
</body>

</html>