Answers for "how to use javascript on button click"

run a function when a button has the onclick

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

click button javascript

// Create variable for what you are trying to click
let button = document.querySelector("#IDofItem");

// Click the button

if (button) {
  button.click();
}
else {
  console.log("Error");
}