Settings menu onchange variable handling

[espruino-discuss2]

Posted at 2023-08-08 by user156125

I'm writing a menu with multiple boolean variable. The menu is populated on load, so I don't know ahead of time how many variables there are or what they are named. I am having an issue saving the value on change. My code is as follows:

data = getDataStreams();
    Object.keys(data).forEach(function(k){
      name = data[k].description.split(" / ")[0];
      if (!settings.keys[name]) {
        // Setting doesn't exist, so we assume it's false
        settings.keys[name] = false;
      }
      submenu[name]= {value:settings.keys[name], onchange: v => {
        settings.keys[name] = v;
        writeSettings();
      }};
    });

the "data" variable looks like this:

[{"description":"DCP battery voltage / USGS-03272100-1964fee2501b43c5b7b807b687319588"},
{"description":"Discharge / USGS-03272100-1db72201226e4f50a94d0b65abc8e7a5"},
{"description":"Gage height / USGS-03272100-56a7245f4b47438cb79c40f0d00605ba"},
{"description":"Temperature, water / USGS-03272100-f8e8a724a5c3498ca11bf1a31be5a537"}]

The submenu populates like this:

{
  "": {
    "title": "-- DataStreams --"
   },
  "< Back": function () {E.showMenu(menu);},
  "DCP battery voltage": { "value": false,
    "onchange": function (v) {
  settings.keys[name] = v;
        writeSettings();
}
   },
  "Discharge": { "value": true,
    "onchange": function (v) {
  settings.keys[name] = v;
        writeSettings();
}
   },
  "Gage height": { "value": true,
    "onchange": function (v) {
  settings.keys[name] = v;
        writeSettings();
}
   },
  "Temperature, water": { "value": true,
    "onchange": function (v) {
  settings.keys[name] = v;
        writeSettings();
}
   }
 }

The issue is that when the "onchange" function runs, name is set to the most recent loop of the foreach, herein "Temperature, water". However, I want it to reflect what the variable "name" was set to when the submenu item was added to the submenu object.

I could convert the function to a string, replace the variable with its value, and then convert back to function within each iteration of the loop, but that strikes me as messy. Does anyone know a better way of doing this?

[espruino-discuss2]

Posted at 2023-08-08 by @gfwilliams

Your issue is you're not defining name locally, so it's a global variable and just ends up filled with the last value you set it to. If you change:

data = getDataStreams();
    Object.keys(data).forEach(function(k){
      name = data[k].description.split(" / ")[0];

to

data = getDataStreams();
    Object.keys(data).forEach(function(k){
      var  name = data[k].description.split(" / ")[0];

Then name ends up defined locally in the function defined inside forEach, so each key in data has its own version of name set.

---

Posted at 2023-08-08 by user156125

That's exactly it, thank you!