mpenkov · December 12, 2015 05:19
diff --git a/clobber.html b/clobber.html
 <!-- 
 vim: shiftwidth=2 
 -->
 <html>
 <head><title>Clobber</title></head>
 <body>
  <form>
    <textarea id="textArea" readonly="true" rows="10" cols="70"></textarea><br/>
    <input id="inputText" type="text" text="Enter some text here" size="50" value="Enter some Unicode here...">
    <input id="checkbox" type="checkbox">clobber the submitted text</input>
    <input type="button" value="Msg" onclick="onSubmit();">
  </form>
  <script>
  // Append the text from inputText to the textArea.  Optionally, clobber the
  // text by encoding it to ASCII prior to appending.
  function onSubmit() {
    var textArea = document.getElementById("textArea");
    var inputText = document.getElementById("inputText");
    if (textArea.value.length > 0)
      textArea.value += "\n";
    var checkbox = document.getElementById("checkbox");
    var text;
    if (checkbox.checked) {
      // If you attempt to represent the string using a limited character set,
      // then the characters that are not supported by that character set will
      // be irrecoverably lost.
      //
      // Note that this problem is not ASCII-specific: any other encoding that
      // does not support the same character set as Unicode, such as KOI-8,
      // will also cause the same problem.
      text = toUtf16(toAscii(inputText.value));
    } else {
      // If you keep characters in JavaScript's native UTF-16, then everything 
      // will work properly, since that encoding supports any character 
      // imaginable.
      text = inputText.value;
    }
    textArea.value += text;
    inputText.value = "";
  }
  // Converts a UTF-16 string to an array of ASCII codes.
  // Non-ASCII characters are replaced with "?", since they cannot be represented
  // by the ASCII character set.  Returns the array.
  function toAscii(utf16) {
    ascii = Array();
    for (var i = 0; i < utf16.length; ++i) {
      code = utf16.charCodeAt(i);
      if (code > 255)
        code = "?".charCodeAt(0);
      ascii[i] = code;
    }
    return ascii;
  }
  // Converts an array of ASCII codes into a normal JavaScript string (signed 
  // UTF-16).  Returns the string.
  function toUtf16(ascii) {
    utf16 = Array();
    for (var i = 0; i < ascii.length; ++i)
      utf16[i] = String.fromCharCode(ascii[i]);
    return utf16.join("");
  }
  </script>
 </body>
 </html>
	<!--
	vim: shiftwidth=2
	-->
	<html>
	<head><title>Clobber</title></head>
	<body>
	<form>
	<textarea id="textArea" readonly="true" rows="10" cols="70"></textarea><br/>
	<input id="inputText" type="text" text="Enter some text here" size="50" value="Enter some Unicode here...">
	<input id="checkbox" type="checkbox">clobber the submitted text</input>
	<input type="button" value="Msg" onclick="onSubmit();">
	</form>
	<script>
	// Append the text from inputText to the textArea. Optionally, clobber the
	// text by encoding it to ASCII prior to appending.
	function onSubmit() {
	var textArea = document.getElementById("textArea");
	var inputText = document.getElementById("inputText");
	if (textArea.value.length > 0)
	textArea.value += "\n";
	var checkbox = document.getElementById("checkbox");
	var text;
	if (checkbox.checked) {
	// If you attempt to represent the string using a limited character set,
	// then the characters that are not supported by that character set will
	// be irrecoverably lost.
	//
	// Note that this problem is not ASCII-specific: any other encoding that
	// does not support the same character set as Unicode, such as KOI-8,
	// will also cause the same problem.
	text = toUtf16(toAscii(inputText.value));
	} else {
	// If you keep characters in JavaScript's native UTF-16, then everything
	// will work properly, since that encoding supports any character
	// imaginable.
	text = inputText.value;
	}
	textArea.value += text;
	inputText.value = "";
	}
	// Converts a UTF-16 string to an array of ASCII codes.
	// Non-ASCII characters are replaced with "?", since they cannot be represented
	// by the ASCII character set. Returns the array.
	function toAscii(utf16) {
	ascii = Array();
	for (var i = 0; i < utf16.length; ++i) {
	code = utf16.charCodeAt(i);
	if (code > 255)
	code = "?".charCodeAt(0);
	ascii[i] = code;
	}
	return ascii;
	}
	// Converts an array of ASCII codes into a normal JavaScript string (signed
	// UTF-16). Returns the string.
	function toUtf16(ascii) {
	utf16 = Array();
	for (var i = 0; i < ascii.length; ++i)
	utf16[i] = String.fromCharCode(ascii[i]);
	return utf16.join("");
	}
	</script>
	</body>
	</html>