How to send POST request to app.js after pressing submit button to show a view and render the values?

Question

I have a number of value 0 on numberMath.ejs. My goal is to press a button. The button will display the view that shows the new value. The new value is calculated by a formula that I wrote in app.js.

Answer 1

If you want the old and the new number to appear you should send through the two as different values on render()

app.post("/numberMath",function(req,res){
  tempNum = num;
  num++;
  res.render("numberMath", {
    myNewNum: num,
    myOldNum: tempNum
  });
});

On the front end you can use javascript to popup the old and new numbers:

<script>
  alert("Old Num: " + <%= myOldNum %> + ", New Num: " + <%= myNewNum %>);
</script>

This will get the two calculated values to the front-end each time you push the Formula button.