Incorrect series order in legend after removing old series and adding new ones.

[Rashaine]

I tracked this down to series.init (series._i = chartSeries.length - 1;) which sets the series sorting index to the length of the series, however this doesn't account for other series which already had a sorting index set above the chartSeries.length.

I also noted while trying to come up with a workaround that series.update() overrides series.options.index with series.index if no new index is provided in the update which seems weird and wrong.

Expected behaviour

Adding a new series should always add it as the last series unless an index is specified.

Actual behaviour

Adding a new series works as expected until existing series are deleted to create gaps/holes in the saved sort indices.

Live demo with steps to reproduce

http://jsfiddle.net/a9pnwwjp/2/

1. Remove 3 series with the remove button.
2. Add new series with the add button and note that the first 2 series added go between series 1 and series 5, then the rest are added after series 5.

Affected browser(s)

Chrome

[TorsteinHonsi]

Thanks for reporting!

Regarding your comment on series.update(), perhaps we should add a check for existing index option:

        // Do the merge, with some forced options
        newOptions = merge(oldOptions, {
            animation: false,
            index: pick(oldOptions.index, this.index), // <= changed here
            pointStart: this.xData[0] // when updating after addPoint
        }, { data: this.options.data }, newOptions);