run a function when a button has the onclick

1var element = document.getElementById("elem");
2element.onclick = function(event) {
3  console.log(event);
4}

1<script>
2function myFunction() {
3  alert("ALERT THIS FUNCTION HAS RUNNED");
4}
5</script>
6<button onclick="myFunction">click to run function</button>

1<script>
2 function myFunction() {
3   alert("ALERT");
4 }
5</script>
6<button onclick="myFunction">Click</button>

1 document.getElementById("Save").onclick = function ()
2    {
3     alert("hello");
4     //validation code to see State field is mandatory.  
5    }

1  <img src="hospital.png" id="hospitals" onclick="damarkers();">