481 remove element

[g105b]

Closes #481

Docs:

Removing elements with a boolean modifier

It's possible to remove an element from the document when a certain condition is true/truthy by marking the element with the data-bind:remove attribute. If the boolean modifier is triggered, the element will be removed from the document.

The inverse logic can be applied by adding an exclamation mark (!) to the start of the bind value.

In this example, a bound object has an isDay boolean property, and the appropriate span is removed from the document, leaving the correct sentence behind:

<p id="day-or-night">Is it day or night? <span data-bind:remove="?isDay">It's nighttime!</span><span data-bind:remove="?!isDay">It's daytime!</span></p>

If the bound object has a truthy isDay property, the span containing "It's nighttime" will be removed, and the span containing "It's daytime" will persist.