js验证ip

 function   isIP(str){     var   ip   =   /^([1-9]|[1-9]\d|1\d{2}|2[0-1]\d|22[0-3])(\.(\d|[1-9]\d|1\d{2}|2[0-4]\d|25[0-5])){3}$/;     return   ip.test(str);     } 

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