<script>
var s=[123456,789456,456123];

function contains(str){
      for(var i=0,len=s.length;i<len;i++){
             if(s[i]==str) return true;
      }
      return false;
}
function foo(o){
      if(!contains(o.value)) document.getElementById('flag').innerHTML='假';
      else
          document.getElementById('flag').innerHTML='真';
}      
</script>
<input type="text" name="qq" id="qq" onblur="foo(this)" /><span id="flag"></span>