window.getSelection get the right selection in textarea

Question

in firefox and chrome window.getSelection is used to get the current selection in document,but is the current selection is in a textarea,the window.getSelection didn't return the selection,but the textarea itself. So,how to the right selection in firefox and chrome?

Answer 1

Do you need to get the selected text in a textarea? You may be asking for selectionStart and selectionEnd (does not exist in Internet Explorer, works with Firefox and Chrome)

 Select some text below and then click the button:<br/>
<textarea id="myTextarea" rows="5" cols="30">
Lorem ipsum dolor sit amet, 
consectetur adipiscing elit.
</textarea>
<button onclick="alert(getTextSelection())">alert text selection</button>

<script type="text/javascript">
    function getTextSelection(){
        var field = document.getElementById("myTextarea");
        var startPos = field.selectionStart;
        var endPos = field.selectionEnd;        
        var field_value = field.value;
        var selectedText = field_value.substring(startPos,endPos);
        return selectedText;
    }   
</script>

If there are multiple textareas and you wish to get the output on select:

Select some text in either textarea:<br/> 
<textarea rows="5" cols="30" onselect="alert(getTextSelection(this))"> 
Lorem ipsum dolor sit amet,  
consectetur adipiscing elit. 
</textarea> 


<textarea rows="5" cols="30" onselect="alert(getTextSelection(this))"> 
fate it seems
not without a sense of irony 
</textarea> 


<script type="text/javascript"> 
    function getTextSelection(field){        
        var startPos = field.selectionStart; 
        var endPos = field.selectionEnd;          
        var selectedText = field.value.substring(startPos,endPos); 
        return selectedText;
    }    
</script>

Or you can still do it with a button but by using a global variable:

Select some text in either textarea and click the button:<br/> 
<textarea rows="5" cols="30" onselect="window.selectedTextarea=this"> 
Lorem ipsum dolor sit amet,  
consectetur adipiscing elit. 
</textarea> 


<textarea rows="5" cols="30" onselect="window.selectedTextarea=this"> 
fate it seems
not without a sense of irony 
</textarea> 



<button onclick="alert(getTextSelection())">alert text selection</button>



<script type="text/javascript"> 
// warning: global variable: dirty!!!
var selectedTextarea

    function getTextSelection(){        
        var field = window.selectedTextarea;
        var startPos = field.selectionStart; 
        var endPos = field.selectionEnd;          
        var selectedText = field.value.substring(startPos,endPos); 
        return selectedText;
    }    
</script> 

Answer 2

Textareas and text inputs have a differenct selection API. They have selectionStart and selectionEnd properties that are character offsets within the value property of the textarea / input. These properties have been standardized in HTML5 and are implemented by the current versions of all major browsers, although IE < 9 has a different API again.