group Delete On Backspace

groupDeleteOnBackspace.js

var BKSPKEY = 8;
handleCommandDelete = function(event,component){
        var messageBox = $(component);
        var valueText  = messageBox.val();

        //get current cursor position 
        if(event.keyCode != BKSPKEY){
            return true;
        }

        var positionObj = updateCursorPosition(messageBox.get(0)) ;

        var startIndex = positionObj.start;
        var endIndex   = positionObj.end;

        //if selection then backspace will delete the selection 
        if(startIndex!=endIndex){
            return true;
        }

        //get back to last space
        for(var index=endIndex;valueText[index]!=' ' && index>=0;index--); 
        startIndex=index;

        var keyword = valueText.substring(startIndex+1, endIndex); 

        // console.log('valueText',valueText);
        // console.log('keyword',keyword);
        

        //check if keyword is special command just select the keyword
        createSelection(messageBox.get(0),startIndex+1,endIndex);
         //if stopPropagation method supported
        if (event && event.stopPropagation){
            event.stopPropagation();
        }
        else{
            event.cancelBubble=true
        }
        return false;
        
       
        return true;
    };
 
 
 
var createSelection = function(field, start, end) {
        if( field.createTextRange ) {
            var selRange = field.createTextRange();
            selRange.collapse(true);
            selRange.moveStart('character', start);
            selRange.moveEnd('character', end);
            selRange.select();
            field.focus();
        } else if( field.setSelectionRange ) {
            field.focus();
            field.setSelectionRange(start, end);
        } else if( typeof field.selectionStart != 'undefined' ) {
            field.selectionStart = start;
            field.selectionEnd = end;
            field.focus();
        }
    }
    
    var updateCursorPosition = function(textBox){
        var positionObj = getCursorPositionInTextBox(textBox);

        $(".mainForm div.message-entry").attr('start',positionObj.start);
        $(".mainForm div.message-entry").attr('end',positionObj.end);

        return positionObj;
    };
    
    var getCursorPositionInTextBox = function(el) {

        /*if(!jqueryElem || jqueryElem.length==0){
            return null;
        }

        el = jqueryElem[0];*/

        var start = 0, end = 0, normalizedValue, range,
            textInputRange, len, endRange;

        if (typeof el.selectionStart == "number" && typeof el.selectionEnd == "number") {
            start = el.selectionStart;
            end = el.selectionEnd;
        } else {
            range = document.selection.createRange();

            if (range && range.parentElement() == el) {
                len = el.value.length;
                normalizedValue = el.value.replace(/\r\n/g, "\n");

                // Create a working TextRange that lives only in the input
                textInputRange = el.createTextRange();
                textInputRange.moveToBookmark(range.getBookmark());

                // Check if the start and end of the selection are at the very end
                // of the input, since moveStart/moveEnd doesn't return what we want
                // in those cases
                endRange = el.createTextRange();
                endRange.collapse(false);

                if (textInputRange.compareEndPoints("StartToEnd", endRange) > -1) {
                    start = end = len;
                } else {
                    start = -textInputRange.moveStart("character", -len);
                    start += normalizedValue.slice(0, start).split("\n").length - 1;

                    if (textInputRange.compareEndPoints("EndToEnd", endRange) > -1) {
                        end = len;
                    } else {
                        end = -textInputRange.moveEnd("character", -len);
                        end += normalizedValue.slice(0, end).split("\n").length - 1;
                    }
                }
            }
        }

        return {
            start: start,
            end: end
        };
    }