# For if statement in Function Block, variable remains local

**URL:** <https://discourse.nodered.org/t/for-if-statement-in-function-block-variable-remains-local/81505>\
**Category:** General\
**Created:** [23 September 2023 03:14 UTC](https://discourse.nodered.org/t/for-if-statement-in-function-block-variable-remains-local/81505 "2023-09-23T03:14:04Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![xytsrm](https://avatars.discourse-cdn.com/v4/letter/x/6de8d8/32.png) [@xytsrm](https://discourse.nodered.org/u/xytsrm)\
**Post date:** [23 September 2023 03:14 UTC](https://discourse.nodered.org/t/for-if-statement-in-function-block-variable-remains-local/81505/1 "2023-09-23T03:14:05Z")

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Please review this code:

> let senState\_msg;  
> if (msg.payload==="On") {  
> let senState\_msg={payload:"Sys08: ASE"};  
> } else {  
> let senState\_msg={payload:"Sys07: SSD"};  
> }
> 
> return senState\_msg;

I've declared the variable senState\_msg prior to the if-block, but the variable of the same name within the if-block remains local. How do I get the value set in the if-block outside?

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**Author:** ![E1cid](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/e1cid/32/77971_2.png) [@E1cid](https://discourse.nodered.org/u/E1cid)\
**Post date:** [23 September 2023 14:52 UTC](https://discourse.nodered.org/t/for-if-statement-in-function-block-variable-remains-local/81505/2 "2023-09-23T14:52:49Z")

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Chatted with @xytsrm he found an answer and I thought it was a good question for future readers so opened to allow a response.

here is the chat

Me  
Hi, That is a good question. I take it you figured out not to declare let again inside the if block.

xytsrm  
Yes, exactly. I don't use Java script too often, I'm far more familiar with Python where there are no explicit declarations. Also, I learned that if you want a variable to be global outside the if-block you need to declare it before the if-block. There was an archaic programming language that I used decades ago where you needed to use "let" all the time, for declarations & assignments; I think that was blinding me to the "let" statements in the if-block.

The funny thing is I summited that code sample to ChatGPT, before I made the declaration prior to the if-block. ChatGPT said the code looked ok, but I needed to make the declaration before the if-block. BUT, then it reprinted my code WITHOUT the "let" in the if-block. Can you believe I still missed the removal of the "let"; it never explicitly said you need to remove the "let" - lol.

Regarding leaving the question on the forum as a "learning experience" you right I probably should have, but I was so embarrassed by what I came to see as an obvious error, I hastily deleted it; I'll consider un-deleting it.

Me  
If you want a global var declare it with `var name;`

Mistakes are easy to overlook we have all been there

This is a great community and I would not worry about embarrasment, there are no stupid questions when learning.

xytsrm  
Thanks for the encouragement - lol

Interestingly, I found the either let, or var works, but you're right var is preferred. I had tried the 'var' but it made no difference to the error, but that was before I realized the real error; the 'let' in the if-block.

Me  
var is global and will be available any where  
let is confined in the { } block only or global if defined outside any { }

preference  
is  
const  
let  
var  
in that order  
const means the var will not change, object defined const must always be an object but you can redefine the properties.

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**Author:** ![system](https://us1.discourse-cdn.com/flex026/uploads/nodered/original/1X/d073cd938eafa2e558d7c2cd59003b3ef4963033.png) [@system](https://discourse.nodered.org/u/system)\
**Post date:** [22 November 2023 14:53 UTC](https://discourse.nodered.org/t/for-if-statement-in-function-block-variable-remains-local/81505/3 "2023-11-22T14:53:31Z")

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