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Object Range Selection and Emulating Word 2007's Formatting Box

Say you're working on a text driven web application and you want to get the selected text in order to see what was selected. With JavaScript that's easy enough, but what if you wanted to know what strongly-typed text was selected in order to recreate the selection later? This would come in tremendously handy if you want to have text annotation capabilities in your application. But, why stop there? If you are going to do that, why not add a nice pop-up window over your selection to give easy access to appropriate toolbox options? That's exactly what Word 2007 gives you and you can do the same in your JavaScript applications.

Implementing these two things involves the following tasks: assign each word (or letter if you want really fine grained control) a container span with an id and then watch for hovering over an object. When an object is hovered over, start a timer counter for the time of the hover. If hovering ends, reset the timer. When a specified amount of hover time has elapsed, see if they is a selection and if the object currently hovered over is in the selection. If so, show the toolbox. The first word and he last word selected are saved in the browser's Selection object as the 'anchorNode' and 'focusNode' objects of the selection, respectively.

Here's the meat:

// Get all spans and iterate through them making sure each REALLY exists and
// making sure each as an id.
var b = document.getElementsByTagName('span');
for(var a in b) {
    if(b[a] && b[a].id) {
    
        // Only use those with an id starting with 'wid'.
        if(b[a].id.substring(0, 3) == 'wid') {
        
            // Set the event that is called at each interval.
            b[a].timercall = function(evt){
            
                // It there is a saved object (see onmouseover event below), 
                // then continue...
                if(gHoverObject) {
                
                    // Increment counter.  When there are 4 timer intervals, 
                    // then get the object information and show the hover box.
                    hoverCounter++;
                    if(hoverCounter > 3) {
                    
                        // Get the text selection
                        var selection = window.getSelection( );
                        
                        // Does the selection contain the object the cursor is currently over?
                        // false means that the object the cursor is over must be fully selected.
                        // That is, half the word being selected won't cut it.
                        if(selection && selection.containsNode(gHoverObject, false)) {
                        
                            // Save the first object id selected and the last object id selected
                            toolboxObj.start = selection.anchorNode.parentNode.id;
                            toolboxObj.end = selection.focusNode.parentNode.id;
                            toolboxObj.style.display = 'block';
                            toolboxObj.style.left = parseInt(gHoverObject.x) + 'px';
                            toolboxObj.style.top = parseInt(gHoverObject.y) + 'px';
                        }
                    }
                }
            };

            b[a].onmouseover = function(evt) {
                // When the object is hovered over, save the object.
                gHoverObject = this;
                gHoverObject.x = evt.pageX;
                gHoverObject.y = evt.pageY;
                
                this.timer = setInterval(this.timercall, 150);
                hoverCounter = 0;
            };
            
            b[a].onmouseout = function(evt) {
                // Destroy the object so the algorithm doesn't run.
                gHoverObject = null;
                clearInterval(this.timer);
                hoverCounter = 0;
            };
        }
    }
}

The provided proof-of-concept demonstration also demonstrates how to setup regular text to be strongly typed. This is simply done by splitting the text by a space and putting each word into a span, then putting each span into a parent object and finally putting that parent object before the original text and deleting the original text. You can view all this happening and see the resulting structure using Firebug for Mozilla Firefox.

The proof-of-concept demonstration provided is for Mozilla Firefox only.  Internet Explorer does NOT have the abilities to do this.

Important Disclaimer: it's not my intention to teach anyone JavaScript. This information is not for someone to simply copy/paste into their own applications. A solid understanding of the DOM, JavaScript syntax and dynamics, and XHTML is required before any true application can be built. So, please do not ask me any "how do I..." questions. When I get those I merely explain the basics and tell the person to figure it out on their own. In other words, I won't do your homework for you.

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