js正則は2桁の小数を検証して数字を検証します.最も簡単な正規表現大全です.

<h3>           ！（      ！）</h3> 
   :    <input type="text" size="20" onkeydown="if(event.keyCode == 13) alert(/^\d+$/.test(this.value));"> 
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   :    <input type="text" size="20" onkeydown="if(event.keyCode == 13) alert(/^-\d+$/.test(this.value));"> 
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 　 :    <input type="text" size="20" onkeydown="if(event.keyCode == 13) alert(/^-?\d+$/.test(this.value));"> 
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   :    <input type="text" size="20" onkeydown="if(event.keyCode == 13) alert(/^\d+\.\d+$/.test(this.value));"> 
<br> 
   :    <input type="text" size="20" onkeydown="if(event.keyCode == 13) alert(/^-\d+\.\d+$/.test(this.value));"> 
<br> 
 　 :    <input type="text" size="20" onkeydown="if(event.keyCode == 13) alert(/^-?\d+\.\d+$/.test(this.value));"> 
<br> 
 　 :    <input type="text" size="20" onkeydown="if(event.keyCode == 13) alert(/^-?\d+\.?\d*$/.test(this.value));"> 
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  1   :<input type="text" size="20" onkeydown="if(event.keyCode == 13) alert(/^-?\d+\.?\d{0,1}$/.test(this.value));"> 
<br> 
  2   :<input type="text" size="20" onkeydown="if(event.keyCode == 13) alert(/^-?\d+\.?\d{0,2}$/.test(this.value));"> 
<br> 
  3   :<input type="text" size="20" onkeydown="if(event.keyCode == 13) alert(/^-?\d+\.?\d{0,3}$/.test(this.value));"> 
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