TypeScript - check if string contains only numbers

In this article, we want to show how in TypeScript using simple regular expressions, check if string contains only numbers.

Example expressions:

1. /^[0-9]+$/
2. /^[0-9]{1,}$/
3. /^\d+$/
4. /^\d{1,}$/ 

As example, we can select first one, and do some test with match() function:

const expression: RegExp = /^[0-9]+$/;
const text: string = '1000500100900';

if (text.match(expression)) {
  console.log('I am number!');
}