Why Is My JavaScript Regular Expression Not Working

JavaScript RegEx Not Working?

Your code checks the legality of a date format using a regular expression, but it always returns false. The issue lies in the construction of the regular expression.

As you're initializing the regular expression from a string, you need to double-quote the backslashes () in the pattern. This is because the string parser treats backslashes as special characters for string constants.

Incorrect Code:

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

Correct Code:

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

Or, even simpler, use regular expression syntax without needing to escape the slashes:

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

Now, the regular expression should correctly match the dates with the format "MM/YYYY". Make sure to double-quote any slashes (/) embedded within the regular expression pattern.

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