In Typescript, How to check if a string is Numeric

📝 Check if a String is Numeric in TypeScript 🎯 Problem So you're working with TypeScript and you want to check if a string is numeric. You tried using the isNaN function, but it throws an error when you pass a non-numeric string. You also noticed that using parseFloat returns false instead of throwing an error. You want to find a better way to perform this check without encountering any issues.

🔍 Understanding the Issue The isNaN function in TypeScript only accepts numeric values. When you pass a non-numeric string, it throws an error. On the other hand, parseFloat tries to convert the string to a numeric representation. If it fails, it returns NaN. However, if it succeeds, it returns the numeric value without throwing an error.

💡 Easy Solution To overcome this issue, you can use a modified function that wraps the parseFloat function and performs additional checks on the result. Here's the modified function that you can use:

static isNaNModified = (inputStr: string) => {
    var numericRepr = parseFloat(inputStr);
    return isNaN(numericRepr) || numericRepr.toString().length != inputStr.length;
}

🔎 Explanation

1. isNaNModified is a static function that takes inputStr as its parameter.

2. It uses parseFloat(inputStr) to convert the string to a numeric representation.

3. The function checks if numericRepr is NaN using isNaN(numericRepr).

4. The function also compares the length of numericRepr.toString() with inputStr.length.

   • If they're not equal, it means there are non-numeric characters present in the string, so the function returns true.

   • If they're equal, it means the string is entirely numeric, so the function returns false.

🚀 Call-to-Action Now that you understand how to check if a string is numeric in TypeScript, try implementing it in your project. If you have any other questions or need further assistance, feel free to leave a comment below. Happy coding! 🎉

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