Simple If statement doesn´t work

[oma]

I am sure it´s an "boy, tt´s so damn easy" question but i can´t see it anyway. I am getting a msg.payload value of 41.1 but my function still returns false:

var watt = msg.payload.value;

if (watt > 20)
    {
        msg.payload = true;
    }
else
    {
        msg.payload = false;
    }
    
return msg

can someone shine a light for me?

[meeki007]

are you sure that msg.payload.value is a number and not alphanumeric?
try this

var watt = Number(msg.payload.value);

if (watt > 20)
    {
        msg.payload = true;
    }
else
    {
        msg.payload = false;
    }
    
return msg

It would help is you could post (copy paste the value of) your msg.payload for use to see.

[Trying_to_learn]

@oma

var watt = msg.payload.value;

My take would be:

var watt = parseInt(msg.payload);

[dceejay]

That won’t work as a) msg.payload is an object and b) the original message already showed that msg.payload.value was a float not an int.

[Trying_to_learn]

Sorry..... I am still not with the language structure.

I believe you can append commands/qualifiers to things and get stuff to happen that way.

So I thought msg.payload.value (particularly when value is bold) was one of these qualifiers and so made msg.payload into a value rather than a string.

My bad.

@dceejay

original message already showed that msg.payload.value was a float not an int.

Is that because of the 41.1 mentioned?

[meeki007]

So I paid no attention to the bolding of .value

To me I saw a unknown msg.payload with a object key of value and the key having a value of 41.1

now how is this value stored?

msg.payload = {
     value : '41.1'
}

or is it

msg.payload = {
     value : 41.1
}

hmmmmm .... thats why I asked for a copy of the msg.payload output from @oma

[oma]

thanks for getting back. The payload is really 41.08:

{"_msgid":"d61780d1.39404","payload":41.08,"topic":""}

which is why

var watt = parseInt(msg.payload);

if (watt > 20)
    {
        msg.payload = true;
    }
else
    {
        msg.payload = false;
    }
    
return msg

works at least as expected. Is this still not the correct way of parsing it despite the fact that it´s working fine?
And one last thing to this: I am sending boolean true if watt > 20. How does the else statement needs to change to simply send nothing? I only want to send something if it´s really above 20 and not send anything at all if its below 20...

[Steve-Mcl]

@oma

How does the else statement needs to change to simply send nothing

return null;

[Colin]

Since the payload is already a number, not a string, you don't need the `parseInt()'. In fact that may (but not sure) convert it to 41.0 since it tells it to make it an int.

@oma

How does the else statement needs to change to simply send nothing?

else
    {
        msg = null;
    }

returning null means don't send any message.

[Edit] I prefer setting msg to null rather than immediately returning null as in a more complex function it is easy to forget later on in the function that you have already returned.

[meeki007]

sorry just woke up Ignore previous post.

[Dirk_L]

You can also use this:

if (watt > 20)
{
msg.payload = true;
return msg
}

This would just return only something if needed.

[Eckehard_070]

sloppy type conversion may be a source of trouble in JS. ("23"<21+1) is false, but (23<"21"+"1") is true, as JS makes a string addition "21"+"1" = "211". Usually the use of Number() is the best solution to ensure numerical values regardless of the source.

[BlackCatPeanut]

@Dirk_L

{
msg.payload = true;
return msg
}

I'm trying to do something very similar. Would you be able to explain why I'm still seeing a reference error:

Inbound payload:

Current function:

What I'm trying to do is trigger a true boolean in order to incorporate an IF statement looking at the illuminance levels. I plan to continue a flow if the light levels are below a certain level. Thanks in advance...

[Steve-Mcl]

In a function node, the input object is named msg

So you would use msg.payload.value

[BlackCatPeanut]

Thanks @Steve-Mcl - I'm very new and working through some Essentials youtube'ing. Appreciate the quick reply!