Pourquoi une RegEx JavaScript ne fonctionne-t-elle pas lors de la validation du format de date ?

JavaScript RegEx Not Working

In a JavaScript code snippet, a regular expression (RegEx) is used to validate the format of a date string ("02/2010"). However, the RegEx test consistently returns false for all input values. Is there an issue with the code?

Answer:

Yes, the issue lies in the construction of the RegEx. When creating a RegEx from a string, it's crucial to double-up the backslashes ("\") to account for the parsing of the string as a JavaScript string constant.

The original RegEx:

var regEx = new RegExp("^(0[1-9]|1[0-2])/\d{4}$", "g");

becomes:

var regEx = new RegExp("^(0[1-9]|1[0-2])\\/\d{4}$", "g");

Alternatively, using RegEx syntax directly eliminates the need for double backslashes:

var regEx = /^(0[1-9]|1[0-2])\/\d{4}$/g;

Explanation:

The RegEx is split into three parts:

• Start of string: "^"

• Date format pattern: "(0[1-9]|1[0-2])\/\d{4}$"

  • Two digits (01-09 or 10-12) followed by a slash "/"
  • Four digits representing the year (\d{4})
• End of string: "$"

The backslashes ensure that the slashes and other characters within the pattern are recognized as part of the RegEx.

Ce qui précède est le contenu détaillé de. pour plus d'informations, suivez d'autres articles connexes sur le site Web de PHP en chinois!