javascript - Detect click on the inner text of the element without wrapping the text in a second element

Question

I have a Div which is as big as half of my page using CSS:

<div id="bigdiv">
     CLICK ON THIS TEXT
</div>

I am trying to write a javascript or jquery code which detects click on the text and not the rest of the element. Is there a way to do that?

Answer 1

Since we cannot listen for events directly on the textNodes themselves, we have to take a more creative path to solving the problem. One thing we can do is look at the coordinates of the click event, and see if it overlaps with a textNode.

First, we'll need a small helper method to help us track whether a set of coordinates exists within a set of constraints. This will make it easier for us to arbitrarily determine if a set of x/y values are within the a set of dimensions:

function isInside ( x, y, rect ) {
    return x >= rect.left  && y >= rect.top
        && x <= rect.right && y <= rect.bottom;
}

This is fairly basic. The x and y values will be numbers, and the rect reference will be an object with at least four properties holding the absolute pixel values representing four corners of a rectangle.

Next, we need a function for cycling through all childNodes that are textNodes, and determining whether a click event took place above one of them:

function textNodeFromPoint( element, x, y ) {
    var node, nodes = element.childNodes, range = document.createRange();
    for ( var i = 0; node = nodes[i], i < nodes.length; i++ ) {
        if ( node.nodeType !== 3 ) continue;
        range.selectNodeContents(node);
        if ( isInside( x, y, range.getBoundingClientRect() ) ) {
            return node;
        }
    }
    return false;
}

With all of this in place, we can now quickly determine if a textNode was directly below the clicked region, and get the value of that node:

element.addEventListener( "click", function ( event ) {
    if ( event.srcElement === this ) {
        var clickedNode = textNodeFromPoint( this, event.clientX, event.clientY );
        if ( clickedNode ) {
            alert( "You clicked: " + clickedNode.nodeValue );
        }
    }
});

Note that the initial condition if ( event.srcElement ) === this allows us to ignore click events originating from nested elements, such as an image or a span tag. Clicks that happen over textNodes will show the parent element as the srcElement, and as such those are the only ones we're concerned with.

You can see the results here: http://jsfiddle.net/jonathansampson/ug3w2xLc/