update jsrrdgraph to new rrdtool

[xfiles27]

An interesting idea, are there plans to develop the project further? Under the new version of the RRD, more complex CDEF functions, STACK support etc ?

[manuelluis]

The initial idea was do the render of the graph in the browser translating the C code to javascript. The use of javascriptRRD (to get the rrdfiles) was only for testing I was hopping that rrdtool would come with some rest interface to get the data but this has not happened.

I really like the look of the rrdtools graphs, but with the domination of grafana seems complicated to see more tools using graphs with the look of rrdtool.

I there is some interest, I have some ideas:

• use WASM to increase the speed
• make the svg graph more interactive: show data when select a line or area.
• define a yaml/json to represent the graph instead of the rrdtool syntax.
• diverge from rrdtool graph. For example, the areas: you cannot specify the color of the line and the color of the area at the same time, rrdtool is painting a line and a area and this complicates the interactivity of the graph.

Also there is some libraries in javascript that use d3.js to graphs with the look and feel of rrdgraph, like:
https://github.com/oetiker/RrdGraphJS

The add of more CDEF functions it's not complicated.
The STACK was not added because it was deprecated.