fix(TableStrategy): correctly determine first row

[bigopon]

fixes #128
fixes #84

From discussion in #46, I think buffer will never stay inside table, so I think this fix is fine. If it's to be changed, this needs to be revised.

About test, i'm not sure what to add

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For folks who are affected by this, you have to temporarily modify the node_modules/aurelia-ui-virtualization as TableStrategy is not exported. Waiting for @EisenbergEffect @AStoker to review and release.

[avrahamcool]

I'm not able to test this with my project. (I'm not sure what file should I be changing).
I'm using a default esnext 0.33.1 cli project (webpack).

but wouldn't it break if the first element of the tbody is actually a fixed one?

<table>
    <tr>
      <th>Index</th>
      <th>Text</th>
    </tr>
    <tbody>
      <tr>
        <td>FIXED ROW 1 INDEX</td>
        <td>FIXED ROW 1 TEXT</td>
      </tr>
      <tr virtual-repeat.for="item of arr">
        <td>${item.index}</td>
        <td>${item.text}</td>
      </tr>
    </tbody>
  </table>

[bigopon]

If you are using webpack, the file should be node_modules/aurelia-ui-virtualization/dist/native-modules/template-strategy (or you can search within the folder the block: TableStrategy)

if it's requirejs / systemjs, then it's node_modules/aurelia-ui-virtualization/dist/amd/template-strategy

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but wouldn't it break if the first element of the tbody is actually a fixed one?

I think so, not sure how to handle this scenarios though

[avrahamcool]

@bigopon
I've tested it in my project - it works fine when I have only rows that are created by the virtual-repeat.
but if I have some fixed rows, and then other rows with the virtual-repeat, the fixed rows disappear after I scroll.

[bigopon]

@avrahamcool We can't have scrollbar within <tbody/>, can we ? If so, I think the usage you described is not possible to support. I hope I'm wrong and wish to see some possible way to tackle this.

[avrahamcool]

@bigopon I think you are right..
but in this case - the virtual repeat should not delete my fixed rows..

[bigopon]

superseded by #140