I have the following regular expression... This one does not allow empty String. How do I have to manipulate?
var phoneReg = new RegExp(/^\+?[0-9]+(\([0-9]+\))?[0-9-]*[0-9]$/i);
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3 Answers
Just use the "zero or one" operator ?, such as:
/^(?:regex)?$/
^
(?:regex) simply makes the concerned ground uncapturable (i.e. no need to change your $X, \X or ?X indexes if any).
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I believe that the following would work:
/^$|^\+?[0-9]+(\([0-9]+\))?[0-9-]*[0-9]$/i
I've inserted ^$| at the beginning of your regex. The pipe (|) is called an "alternation" indicator and says that either the expression before it or after it must match. ^$ will simply match a string with no characters between the start and end of input. The result: an empty string or the original expression.
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JDB
@user2286914 - Can you be more specific? Seems to work just fine here: regex101.com/r/cP2mD4
You can put a ^$| in front which in which ^ = beginning, $ = end, | = or this other thing to the right.
var phoneReg = new RegExp(/^$|^\+?[0-9]+(\([0-9]+\))?[0-9-]*[0-9]$/i);
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JDB
@user2286914 - Visual Studio's interpretation of JavaScript is not of any particular importance (and is often wrong). Have you actually tried it in the browser?