Hi,
I'm struggling with a simple math function in my Node Red flow.
This doesn't work:
maxBattery = ((80-(100*(sum/1000)/15.4)).toFixed(2))+20; msg.payload = maxBattery; return msg;
This does:
maxBattery = 80-(100*(sum/1000)/15.4)).toFixed(2); msg.payload = Number(maxBattery)+20; return msg;
Why?
Hi @Diederik
Dynamic typing strikes again....
I'm pretty sure this is because javascript is treating first code snip you provided as a string so the + 20 is concatenating 20 as a string rather than evaluating the expression as you expect.
However you're telling JS maxBattery is of type Number in your second option so it's adding the number using addition not concatenation
This might make it easier to follow Assuming sum = 1000
Code snip 1:
maxBattery = ((80 - (100 * (1000 / 1000) / 15.4)).toFixed(2)) + 20
= ((80 - (100 * 1 / 15.4)).toFixed(2)) + 20
= ((80 - 6.493506493506493).toFixed(2)) + 20
= ("73.51") + 20
= "73.51" + "20"
= "73.5120"
Code snip 2:
maxBattery = ((80 - (100 * (1000 / 1000) / 15.4) + 20).toFixed(2))
= ((80 - (100 * 1 / 15.4) + 20).toFixed(2))
= ((80 - 6.493506493506493 + 20).toFixed(2))
= ((93.5064935064935 + 20).toFixed(2))
= (113.5064935064935.toFixed(2))
= "113.51"
Hi @matt1309,
Dynamic Typing :-)
I'm getting an array from the Solar Yield Forecast.
This is the complete function. Where do I start using strings?
var acThreshold = 400;
var sum = 0;
var toAdd = 0;
for (let i = 24; i < 48; i++) {
if (msg.payload.records.solar_yield_forecast[i][1] > acThreshold){
toAdd = msg.payload.records.solar_yield_forecast[i][1]-acThreshold;
}
else{
toAdd = 0;
}
sum += toAdd;
}
//maxBattery = ((80-(100*(sum/1000)/15.4)).toFixed(2))+20;
maxBattery = (80-(100*(sum/1000)/15.4)).toFixed(2);
msg.payload = Number(maxBattery)+20;
return msg;
