Simple Regular Expression application _ only include _

Varreg/(\ w + [_ & amp;] + $) | ([_ & amp;] + \ w + $) | (^ [A-Za-z0-9] + $ )/; if (! Reg. test (value_name) {// TODO .............} www.2cto.com/(\ w + [_ & amp;] + $) | ([_ & amp;] + \ w + $) | (^ [A-Za-z0-9 var reg =/(\ w + [_ &] + $) | ([_ &] + \ w + $) | (^ [A-Za-z0-9] + $)/; if (! Reg. test (value_name) {// TODO .............} www.2cto.com/(\ w + [_ &] + $) | ([_ &] + \ w + $) | (^ [A-Za-z0-9] + $) /// it is used to generate a String str = "sss" equivalent to java; double quotation marks \ w can only be numbers and letters, case-insensitive [_ &] underscores and & conformances can both have one + Yes yes (^ [A-Za-z0-9] + $) it is a string that can only start with a number or a letter. + $ is the end, meaning that there cannot be anything else (except numbers and letters, case-insensitive)