new to JavaScript, simple if function

Question

I just made the jump from IDE to Node-RED where JavaScript comes into play. I am eager to learn but my knowledge is limited knowledge.

What I am trying to do, is simple to check the msg.payload , if the value is larger than 25 then I want to return 1 else I want to return 0.

I have tried different codes, but it does not work.

m = msg.payload;
if (m < 25)
{
  return 1;
}
else if (m > 25)
{
  return 0;
}

and

m = msg.payload;
if (m < 25)
{
  return 1;
}
  else ()
{
  return 0;
}

Answer 1

For Node-RED function nodes you must return a msg object not just a value.

So the correct form for this test is as follows.

if (msg.payload > 25) {
  msg.payload = 1
} else {
  msg.payload = 0;
}

return msg;

Answer 2

You should learn comparision operator where > denotes greater than and < denotes lesser than , you can simplify using ternary operator as

return msg.payload > 25 ? 1 : 0; 

DEMO WITH IF ELSE

 function check(m){ if (m > 25){ return 1; } else { return 0; } }; console.log(check(50)); 

DEMO WITH TERNARY

 function check(m){ return m > 25 ? 1 : 0; }; console.log(check(50)); 

Answer 3

You can do it in one line:

return msg.payload > 25 ? 1 : 0;

or if you just need booleans (true/false):

return msg.payload > 25;

Answer 4

Try this:

if (Number(m) > 25){
    return 1;
}
else{
    return 0;
}

Answer 5

You are making a very silly mistake of less than and greater than sign. Hope it helps you.

m = msg.payload;
if (m > 25)
{
msg.payload=1;
}
else if (m < 25)
{
msg.payload=0;
}
return msg;

Answer 6

You can simplify this a good bit, the else isn't even needed in this case:

if (m > 25) {
  return 1;
}
return 0;

When the return inside the if statement is executed, the code that follows won't be run... making the else statement unnecessary.

Answer 7

The else is redundant when you're just returning like that, and you've got your comparison operators backwards. Right now it'll return 1 if it's less than 25, not greater than.

if (msg.payload > 25) {
return 1;
}
return 0;

Answer 8

As you have mentioned that you want to return 1 if value is greater than 25. Please check that you have written wrong condition. Your condition must be this:

if ( m > 25 ){ 
    return 1; 
} else { 
    return 0; 
}