JavaScript/validations.html at main · sudeepnagar/JavaScript · GitHub

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<!--Validations =>checking user inputs
				=>form Validations/client side Validations/js Validations

				reg exp=>
				Regular expressions or regex are patterns are used to match
				character combinations in strings.

				you can create a regex pattern using the `RegExp` constructor or
				by using regex literals enclosed in slash
				syn:
				   const refvar= new RedExp(pattern);
				   const refvar= /pattern/;

				   refvar.test(data)=>true,false

        they are called wild card characters
				   word  => /ram/        ->user name should contain ram like ram or rama or raman
				   /i    =>/ram/i  (ignore case)
				   /g    =>/ram/g  (global)
				   /w    =>/ram/w  (word)
				   [p1p2p3...] => multiple patterns (or) =>its like [p1 or p2 or p3 ] but we cannot write or
				   -   => range    a-f
				   \d  => digits
				   \s  => symbol
				   *   => any no of char
				   {count} => {10}
				   {min,max} => {5,10}
				   (?=.p1)(?=.p2)(?=.p3) => and

				   syn:  /^           $/
				-->
<!DOCTYPE html>
<html lang="em">
<head>
      <meta charset="UTF-8">

</head>
<body>
      <input type="text" id="un">
	  <button onclick="checkUser()">Check user</button>


        <script>

		function checkUser()
		{
		   const exp=new RegExp(/siva/i);
		  //const exp=/shiva/;
		  alert(exp.test(un.value));
		}


		</script>

</body>
</html>