_Actual_ Twitter format for hashtags? Not your regex, not his code— the actual one?

Question

Update: Use Twitter\'s Entities if you can- they figured it out for you as well as other items. My case is that I just have the tweet without entities and all the extra metadat

Answer 1

There is in fact an official specification for hashtags. Twitter accepts only a subset of Unicode expressions for the hashtag syntax. Here is the regular expression to recognize all valid Hashtags used on Twitter (pulled from their own sourcecode.)

To see how it's generated see the source code of twitter-text.

/(#|＃)([a-z0-9_\u00c0-\u00d6\u00d8-\u00f6\u00f8-\u00ff\u0100-\u024f\u0253-\u0254\u0256-\u0257\u0300-\u036f\u1e00-\u1eff\u0400-\u04ff\u0500-\u0527\u2de0-\u2dff\ua640-\ua69f\u0591-\u05bf\u05c1-\u05c2\u05c4-\u05c5\u05d0-\u05ea\u05f0-\u05f4\ufb12-\ufb28\ufb2a-\ufb36\ufb38-\ufb3c\ufb40-\ufb41\ufb43-\ufb44\ufb46-\ufb4f\u0610-\u061a\u0620-\u065f\u066e-\u06d3\u06d5-\u06dc\u06de-\u06e8\u06ea-\u06ef\u06fa-\u06fc\u0750-\u077f\u08a2-\u08ac\u08e4-\u08fe\ufb50-\ufbb1\ufbd3-\ufd3d\ufd50-\ufd8f\ufd92-\ufdc7\ufdf0-\ufdfb\ufe70-\ufe74\ufe76-\ufefc\u200c-\u200c\u0e01-\u0e3a\u0e40-\u0e4e\u1100-\u11ff\u3130-\u3185\ua960-\ua97f\uac00-\ud7af\ud7b0-\ud7ff\uffa1-\uffdc\u30a1-\u30fa\u30fc-\u30fe\uff66-\uff9f\uff10-\uff19\uff21-\uff3a\uff41-\uff5a\u3041-\u3096\u3099-\u309e\u3400-\u4dbf\u4e00-\u9fff\u20000-\u2a6df\u2a700-\u2b73f\u2b740-\u2b81f\u2f800-\u2fa1f]*[a-z_\u00c0-\u00d6\u00d8-\u00f6\u00f8-\u00ff\u0100-\u024f\u0253-\u0254\u0256-\u0257\u0300-\u036f\u1e00-\u1eff\u0400-\u04ff\u0500-\u0527\u2de0-\u2dff\ua640-\ua69f\u0591-\u05bf\u05c1-\u05c2\u05c4-\u05c5\u05d0-\u05ea\u05f0-\u05f4\ufb12-\ufb28\ufb2a-\ufb36\ufb38-\ufb3c\ufb40-\ufb41\ufb43-\ufb44\ufb46-\ufb4f\u0610-\u061a\u0620-\u065f\u066e-\u06d3\u06d5-\u06dc\u06de-\u06e8\u06ea-\u06ef\u06fa-\u06fc\u0750-\u077f\u08a2-\u08ac\u08e4-\u08fe\ufb50-\ufbb1\ufbd3-\ufd3d\ufd50-\ufd8f\ufd92-\ufdc7\ufdf0-\ufdfb\ufe70-\ufe74\ufe76-\ufefc\u200c-\u200c\u0e01-\u0e3a\u0e40-\u0e4e\u1100-\u11ff\u3130-\u3185\ua960-\ua97f\uac00-\ud7af\ud7b0-\ud7ff\uffa1-\uffdc\u30a1-\u30fa\u30fc-\u30fe\uff66-\uff9f\uff10-\uff19\uff21-\uff3a\uff41-\uff5a\u3041-\u3096\u3099-\u309e\u3400-\u4dbf\u4e00-\u9fff\u20000-\u2a6df\u2a700-\u2b73f\u2b740-\u2b81f\u2f800-\u2fa1f][a-z0-9_\u00c0-\u00d6\u00d8-\u00f6\u00f8-\u00ff\u0100-\u024f\u0253-\u0254\u0256-\u0257\u0300-\u036f\u1e00-\u1eff\u0400-\u04ff\u0500-\u0527\u2de0-\u2dff\ua640-\ua69f\u0591-\u05bf\u05c1-\u05c2\u05c4-\u05c5\u05d0-\u05ea\u05f0-\u05f4\ufb12-\ufb28\ufb2a-\ufb36\ufb38-\ufb3c\ufb40-\ufb41\ufb43-\ufb44\ufb46-\ufb4f\u0610-\u061a\u0620-\u065f\u066e-\u06d3\u06d5-\u06dc\u06de-\u06e8\u06ea-\u06ef\u06fa-\u06fc\u0750-\u077f\u08a2-\u08ac\u08e4-\u08fe\ufb50-\ufbb1\ufbd3-\ufd3d\ufd50-\ufd8f\ufd92-\ufdc7\ufdf0-\ufdfb\ufe70-\ufe74\ufe76-\ufefc\u200c-\u200c\u0e01-\u0e3a\u0e40-\u0e4e\u1100-\u11ff\u3130-\u3185\ua960-\ua97f\uac00-\ud7af\ud7b0-\ud7ff\uffa1-\uffdc\u30a1-\u30fa\u30fc-\u30fe\uff66-\uff9f\uff10-\uff19\uff21-\uff3a\uff41-\uff5a\u3041-\u3096\u3099-\u309e\u3400-\u4dbf\u4e00-\u9fff\u20000-\u2a6df\u2a700-\u2b73f\u2b740-\u2b81f\u2f800-\u2fa1f]*)/gi