How to Implement a Custom Numeric Check Function in Pure JavaScript?

Pure JavaScript: Function to Check if a Value is Numeric

In jQuery, the isNumeric() function verifies whether a value represents an integer. While JavaScript does not have a similar built-in function, you can implement your own custom check.

To create a function that mimics isNumeric() in pure JavaScript, follow these steps:

1. Define the isNumeric() Function:

   <code class="javascript">function isNumeric(n) {</code>

2. Check if the Value is a Number:

   Use !isNaN(parseFloat(n)) to determine if the value can be successfully parsed as a floating-point number.

3. Ensure the Value is Finite:

   Add && isFinite(n) to verify that the number is finite, excluding Infinity and NaN.

4. Complete the Function Definition:

   <code class="javascript">  return !isNaN(parseFloat(n)) &amp;&amp; isFinite(n);
   }</code>

Example Usage:

<code class="javascript">const value = 123;
const isNumber = isNumeric(value); // Returns true</code>

Note:

It's important to avoid using parseInt() to check for numeric values. While it may initially appear to work, it can lead to unexpected results and is not a reliable way to determine numeric values in JavaScript.

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