Substring() error - how to get around it?

General
1

I hope this is the part of the code which is throwing an error.

var led = parseInt(led_msg.substring(4,5)) || 0;

How can I wrap this so if it doesn't exist that it gives a 0.

2

Hi Andrew .. maybe you can try to check if led_msg has a truthy value (if it exists)
before trying to substring or parseInt it.

var led = led_msg ? parseInt(led_msg.substring(4,5)) : 0

The ? and : is just a funcy way of writing if statements in one line
Which translates to

led_msg ? does led_msg have value ?
if yes do parseInt(led_msg.substring(4,5))
if not : set to 0

3

Thanks.

That magic is beyond me and my knowledge.

So if I put that line in, in place of the existing one, all should be ok?

4

yes .. replace it, fingers crossed that thats the problem ..
it does more or less the same with the only difference that it checks first if led_msg has a value.

5

Thanks.

That's fixed THAT problem. Now on to the ever growing list of others. :wink:

1 Like
6

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