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<!DOCTYPE html>
<html>
<body>
​
<h2>JavaScript Closures</h2>
<p>Counting with a local variable.</p>
​
<button type="button" onclick="myFunction()">Count!</button>
​
<p id="demo">0</p>
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<script>
// Function to increment counter
function add() {
  let counter = 0;
  counter += 1;
  return counter;
}
// Trying to increment the counter
function myFunction(){
  document.getElementById("demo").innerHTML = add();
}
</script>
​
</body>
</html>
​