number regex from 0 to x code example
Example 1: regex match any number of digits
For matching an integer number of one single char/digit, specify:
[0-9]
But for matching any number of more than one char/digit; add "+":
[0-9]+
Example for matching hour with minutes of HH:MM format in a file:
grep "[0-9]\+\:[0-9]\+" file.txt
Example 2: javascript regex zero or more occurrence
// /x*/ - Regular Expression zero or more occurrence
console.log(/'\d*'/.test("'123'"));// true
console.log(/'\d*'/.test("''"));// true