Exercise 13: Check if String Contains Only Digits
Problem Statement
Create a function `isNumeric(str)` that checks if string contains only digits.
Example:
- isNumeric("123") → true
- isNumeric("12a") → false
Sample Output:
isNumeric("123") => true
isNumeric("12a") => false
isNumeric("") => falseSolution
const isNumeric = (str) => {
const s = String(str ?? "");
return s.length > 0 && /^\d+$/.test(s);
};Explanation
Overall Goal:
- String me sirf digits hain ya nahi check karna.
Line 1: Function header
const isNumeric = (str) => {
Line 2: Convert
const s = String(str ?? "");
Line 3: Regex test
return s.length > 0 && /^\d+$/.test(s);^\d+$→ start se end tak sirf digits.
Real world:
- Form validation: numeric inputs.
- Data validation: number strings.