Re: [Edbrowse-dev] infinite loop js while()

[Kevin Carhart <kevin@carhart.net>]

This is great!  Very exciting!


On Sat, 28 Jan 2017, Karl Dahlke wrote:

> After some detective work, here is the js that causes the infinite loop.
> It creates two nodes, ft and fg, uses ft.innerHTML to put some nodes beneath ft,
> then has a while loop that, I assume, moves the nodes from ft to fg.
> Here's the code, then more thoughts below.
>
> var rid=oio.at_ei,fg=document.createDocumentFragment(),ft=document.createElement('div');
> ft.innerHTML='<'+'div class="'+oio.at_ec+'" id="'+rid+'" style="'+oio.at_es+'">&nbsp;'+'<'+'/div'+'>';
> while(ft.firstChild)fg.appendChild(ft.firstChild);
> document.body.insertBefore(fg,document.body.childNodes[0]);
>
> Ok, so the generated html looks like this.
>
> <div class="MBoxAdMain gp-ui" id="sponsoredwellcontainertop" style="position:absolute;display:block;">&nbsp;</div>
>
> Running through innerHTML, that creates a node under ft.
> All good so far.
> Then comes the while loop, and the only way this isn't an infinite loop is if appendChild removes the node first from wherever it is, then appends it.
> I've been talking about this on the edbrowse side, in our own tree of nodes, but here it is on the js side, strictly within dom, and it's the same issue.
> I think this is not just compelling evidence, but a smoking gun.
> Even if it doesn't say so in the spec, appendChild and insertBefore should remove the child from wherever it is first, then put it beneath the new node.
> Then the while loop above simply moves all the children from ft to fg.  Zip zap.
>
> I'm going to think about this for a bit, cause if I just start writing code I'll screw it up, but I'm pretty sure I understand the problem now.
> I just need to fix it with a small amount of code, and not breaking anything else.
> I imagine if I fix it on the js side, by issuing a remove when necessary, before the append, then all those actions will carry over to the edbrowse side in our sideEffects, and I won't have to change any code over there, it will just all work.
>
> Karl Dahlke
>

--------
Kevin Carhart * 415 225 5306 * The Ten Ninety Nihilists