How do I check if a string represents a number (float or int)?

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You can use JavaScript to check if a string represents a number (integer or floating-point) using various methods. One common approach is to use the isNaN() function to determine if the string can be converted into a valid number. Here's an example:

html

<!DOCTYPE html>
<html>
<head>
  <title>Check if String is a Number</title>
</head>
<body>

<script>
function isNumeric(str) {
  return !isNaN(str);
}

const stringsToCheck = ["123", "3.14", "abc", "-45", "2e5"];

stringsToCheck.forEach(str => {
  if (isNumeric(str)) {
    console.log(`${str} is a number.`);
  } else {
    console.log(`${str} is not a number.`);
  }
});
</script>

</body>
</html>

In this example, the isNumeric() function checks whether the given string can be converted into a number. The isNaN() function returns true if the input is Not-a-Number (NaN), so we use the negation operator (!) to reverse the result and determine if the string represents a number.

The stringsToCheck array contains different strings, some of which represent numbers and others that don't. The forEach() loop iterates through each string and logs whether it is a number or not.

When you run this code, you'll see the output indicating which strings are numbers and which are not.

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