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<html><head><meta charset="UTF-8"><title>Insert title here</title></head><body> <h2> Javascript </h2> <!-- <script> var str = 'adcdefg';//用户名 var reg = /^[a-zA-Z\d]\w{3,11}[a-zA-Z\d]$/;//正则 if(reg.test(str)){ alert('验证成功'); }else{ alert('验证失败'); } </script> --> <script> var uPattern = /^[a-zA-Z0-9_-]{4,16}$/; //输出 true console.log(uPattern.test("lAl520_-")); </script></body></html>