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The simplest JavaScript validates integer decimal real and valid decimal regular expressions

  • 2020-05-30 19:23:55
  • OfStack 

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> 
<html xmlns="http://www.w3.org/1999/xhtml"> 
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<title>  Verify that the number is the simplest of all regular expressions  </title> 
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<h3> After typing, press enter to verify! (think it's the easiest!) </h3> 
 Positive integer :  <input type="text" size="20" onkeydown="if(event.keyCode == 13) alert(/^/d+$/.test(this.value));" /> 
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 Negative integer :  <input type="text" size="20" onkeydown="if(event.keyCode == 13) alert(/^-/d+$/.test(this.value));" /> 
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 The integer :  <input type="text" size="20" onkeydown="if(event.keyCode == 13) alert(/^-?/d+$/.test(this.value));" /> 
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 Is the decimal :  <input type="text" size="20" onkeydown="if(event.keyCode == 13) alert(/^/d+/./d+$/.test(this.value));" /> 
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 Negative decimal :  <input type="text" size="20" onkeydown="if(event.keyCode == 13) alert(/^-/d+/./d+$/.test(this.value));" /> 
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 The decimal :  <input type="text" size="20" onkeydown="if(event.keyCode == 13) alert(/^-?/d+/./d+$/.test(this.value));" /> 
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 The set of real Numbers :  <input type="text" size="20" onkeydown="if(event.keyCode == 13) alert(/^-?/d+(/./d+)?$/.test(this.value));" /> 
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 keep 1 Decimal places :<input type="text" size="20" onkeydown="if(event.keyCode == 13) alert(/^-?/d+(/./d{1,1})?$/.test(this.value));" /> 
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 keep 2 Decimal places :<input type="text" size="20" onkeydown="if(event.keyCode == 13) alert(/^-?/d+(/./d{1,2})?$/.test(this.value));" /> 
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 keep 3 Decimal places :<input type="text" size="20" onkeydown="if(event.keyCode == 13) alert(/^-?/d+(/./d{1,3})?$/.test(this.value));" /> 
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</body> 
</html>

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