Cannot assign the value of a textbox to a variable

Question

I'm trying to read the value from a textbox and it returns nothing.

Within the console, it simply shows a white line, with the line number of the console.log statement.

var amount = document.getElementById("billAmt").value;
document.getElementById('calculate').addEventListener('click', function() {
  console.log(amount);
});

<input id="billamt" type="text" placeholder="Bill Amount">
<button type="button" id="calculate">Calculate!</button>

`amount` does not magically update. Put your `var` inside your event handler, where you actually want to use it. — Niet the Dark Absol, Aug 27 '18 at 11:55
_This question was caused by a problem that can no longer be reproduced or a simple typographical error. While similar questions may be on-topic here, this one was resolved in a manner unlikely to help future readers. This can often be avoided by identifying and closely inspecting the shortest program necessary to reproduce the problem before posting_ — mplungjan, Aug 27 '18 at 11:58
Welcome to SO. Feel free to delete the question since it is not really useful to anyone but you — mplungjan, Aug 27 '18 at 11:58
1. https://stackoverflow.com/questions/20500434/why-wont-this-simple-event-listener-work-in-javascript — mplungjan, Aug 27 '18 at 12:11
Alternative: https://stackoverflow.com/questions/1759987/listening-for-variable-changes-in-javascript — mplungjan, Aug 27 '18 at 12:16

score 0 · Answer 1 · answered Aug 27 '18 at 11:56

There are couple of issues in your code:

Typo in billamt. It should be billAmt in HTML or change either of them to make same
You need to get the value inside the click function.

document.getElementById('calculate').addEventListener('click', function() {
  var amount = document.getElementById("billAmt").value;
  console.log(amount);

});

<input id="billAmt" type="text" placeholder="Bill Amount">
<button type="button" id="calculate">Calculate!</button>

Done! Thank you very much! – Nicolae Munteanu Aug 27 '18 at 11:57 — Nicolae Munteanu, Aug 27 '18 at 11:57

Cannot assign the value of a textbox to a variable

1 Answers1