If statement in Node red (javascript)

Question

I'm trying to evaluate a value in node red :

from the join node I'm getting the following:

so what I'm trying to do in the function is to check the 1. sent value:

var payload  = msg.payload; 
if (msg.payload[0] === "0" ){
    msg.payload  =0;
} else {
    msg.payload = 1;
}

//msg.payload = payload[0];
return msg;

So my question why am I getting the if statement is false ?

thanks for any hint

SBylemans · Accepted Answer · 2018-10-08 09:07:47Z

3

Not sure what you are trying to check but checking the value of the payload property can be done as follows:

if(typeof msg.payload === "object"){
    if(msg.payload[0].value === 0) { // Use "0" if this value is a string, but I guess not by inspecting your data.
        // Your code
    } else {
        // Other code
    }
}
else {
    // msg.payload is not an array
}

According to your data, you have two situations, either msg.payload is an array or either it is a value.

answered Oct 8, 2018 at 9:07

SBylemans

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1 Comment

holydragon Over a year ago

Allow me to add one explanation here for some who don't know. msg.payload is actually an array but with "typeof" it will return "object". Reference: developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/…

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