document.selection.createRange() not working in chrome and safari

I am using a textbox with te开发者_开发问答xtmode as multiline option its working fine in IE,Mozilla problem occurs in Chrome and safari. Sample code folows

<asp:TextBox ID="txtRootDescription" onpaste="DoPaste(this);" Width="600px" Rows="10" Columns="72" MaxLength="500" TextMode="MultiLine" runat="server"></asp:TextBox>

function DoPaste(control) {
maxLength = control.attributes["maxlength"].value;   
if (maxLength) {        
    var oTR = control.document.selection.createRange();     
}}

in chrome it gives me an error as "Cannot read property 'selection' of undefined"

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In non IE (excluding IE9) browsers (see comments), use window.getSelection to get the selection object. In IE < 9, original code should work.

function GetSelection () {
    if (window.getSelection) {  // all browsers, except IE before version 9
        var selectionRange = window.getSelection ();                                        
        return selectionRange.toString();
    } 
    else {
        if (document.selection.type == 'None') {
            return "";
        }
        else {
            var textRange = document.selection.createRange ();
            return textRange.text;
        }
    }
}

function DoPaste(control) {
    maxLength = control.attributes["maxlength"].value;   
    if (maxLength) {        
        var oTR = GetSelection();     
    }
}

In general, working with selection and ranges is very tricky as browser supports varies so much.

Here's an excellent reference which lists out browser support (and what code works where) and sample code that works in corresponding browsers: http://help.dottoro.com/ljefwsqm.php

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There are a number of foibles when getting selected text in a document, mostly related to whether or not text is selected in a form control or as text of some other element. Try a function that does something like:

function checkForSelectedText(e) {
  var e = e || window.event;
  var el = e.target || e.srcElement;
  var tagName = el.tagName && el.tagName.toLowerCase();
  var t;
  var d = document;

  // Try DOM 2 Range - for most browsers, including IE 6+
  // However, doesn't get text selected inside form controls
  // that allow selection of text content (input type text, 
  // textarea)
  if (d && d.selection && d.selection.createRange) {
    t = d.selection.createRange().text;

  // Otherwise try HTML5 - note that getSelection returns
  // a string with extra properties. This may also get
  // text within input and textarea
  } else if (d.getSelection) {
    t = d.getSelection();
  }

  // If didn't get any text, see if event was inside
  // inupt@type=text or textarea and look for text
  if (t == '') {
    if (tagName == 'textarea' || 
       (tagName == 'input' && el.type == 'text')) {

     // Check selectionStart/End as otherwise if no text
     // selected, IE returns entire text of element
     if (typeof el.selectionStart == 'number' && 
         el.selectionStart != el.selectionEnd) {
        t = el.value.substring(el.selectionStart, el.selectionEnd)
     }
    }
  }
  return t;
}

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I would use JQuery to do the same because it's cross browser and you write more abstract java script instead of the native browser specific one your wrote so far.