Practical_ assign_0.html

<!doctype html>
<html>
<head>
  <div class="encrypt">
    <h2>Encrypt/decrypt Text</h2>
    <input  type="text" placeholder="Enter Text" id="ptxtt" >
    <button onclick="convert1()">convert</button>
    <input  type="text" placeholder="output Text" id="outptt">
  </div>
</head>

<script>

function convert1() //function for encrypt/decrypt text.
{
  var outpt;  //assigning output variable for final conversion.
  
  var ptxt = $("#ptxtt").val();  //reading input text and storing in variable.

  outpt=''; //initialising empty string
  var c;   //initialising variable.
  for(var i=0;i<ptxt.length;i++) // loop over input string length.
  {
    
    if(ptxt[i]>='a' && ptxt[i]<='z') //check condition for lowercase letters. 
    {
    var t=216-ptxt.charCodeAt(i); //getting reverse ascii number for alphabet.
    c=String.fromCharCode(t);   //converting to string from reverse ascci number.
    outpt+=c; // adding character in final string.
    }
    else if(ptxt[i]>='A' && ptxt[i]<='Z') //check condition for uppercase letters. 
    {
    var t=155-ch.charCodeAt(0); //getting reverse ascii number for alphabet.
    c=String.fromCharCode(t); //converting to string from reverse ascci number.
    outpt+=c; //adding character in final string.
    }
    else //condition if character is not alphabet letters.
    {outpt+=ptxt[i];}

  }
  document.getElementById("outptt").value = outpt; // storing output value and initialising to original id.
  
}
</script>

</html>