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<input id="username" onkeyup="check()"/><span id="inf_n"></span>
<script>
function check(){
var name=document.getElementById("username").value;
var sp_inf_n=document.getElementById("inf_n");
if(name){
sp_inf_n.style="color:green;";
sp_inf_n.innerHTML="*â";
}else{
sp_inf_n.style="color:red";
sp_inf_n.innerHTML="*请è¾å
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容ï¼"
}
}
</script>
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