Handling repeated "derivative" values

[TLATER]

Hi, I'm finally starting to use eww for more than super simple things, and I'm finding myself writing things like this:

(defwidget _battery_icon []
           (label :text {
                    EWW_BATTERY == "" ? "" :
                    jq(EWW_BATTERY, "first(.[])").status == "Charging" ?
                    "" :
                    jq(EWW_BATTERY, "first(.[])").capacity > 75 ?
                    "" :
                    jq(EWW_BATTERY, "first(.[])").capacity > 50 ?
                    "" :
                    jq(EWW_BATTERY, "first(.[])").capacity > 25 ?
                    "" :
                    jq(EWW_BATTERY, "first(.[])").capacity > 5 ?
                    "" :
                    ""
                    }
                  :visible {EWW_BATTERY != ""}
                  :tooltip "${EWW_BATTERY == "" ? "" : jq(EWW_BATTERY, "first(.[])").capacity}%"))

This is... Obviously rather unwieldy. Besides the if/else chain in ternary syntax, there's a bunch of code for special casing on jq output, and I'm sure this adds all kinds of pointless overhead parsing json over and over again.

Is there a way to get e.g. the output of jq(EWW_BATTERY, "first(.[])" in some kind of temporary variable so I can skip all that code? Is this what #430 is about?