# Function node code editor warnings
**URL:** https://discourse.nodered.org/t/function-node-code-editor-warnings/14748
**Category:** General
**Created:** [24 August 2019 20:08 UTC](https://discourse.nodered.org/t/function-node-code-editor-warnings/14748 "2019-08-24T20:08:02Z")
**Posts on this page:** 8
**Page:** 1
### Author:  [@thatcadguy](https://discourse.nodered.org/u/thatcadguy)
#### Post date: [24 August 2019 20:08 UTC](https://discourse.nodered.org/t/function-node-code-editor-warnings/14748/1 "2019-08-24T20:08:02Z")
Are these warnings/errors displayed by the line numbers part of Node-RED's codebase, or is this functionality from another library?
The warnings/errors shown are wrong sometimes, e.g. defining a variable with var inside an if statement and then using it right after says it's out of scope (that would be true for let or const, not var).
---
### Author:  [@knolleary](https://discourse.nodered.org/u/knolleary)
#### Post date: [24 August 2019 20:11 UTC](https://discourse.nodered.org/t/function-node-code-editor-warnings/14748/2 "2019-08-24T20:11:47Z")
It is the JavaScript parser that the ACE editor comes with.
I know it trips over some of the newer ES6 syntax.
Can you provide some specific examples?
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### Author:  [@thatcadguy](https://discourse.nodered.org/u/thatcadguy)
#### Post date: [24 August 2019 20:19 UTC](https://discourse.nodered.org/t/function-node-code-editor-warnings/14748/3 "2019-08-24T20:19:35Z")
This is within a function definition:
```auto
// create request data
if ([3, 4, 5, 6].includes(fc)) {
var n = 2;
var reqd = Buffer.from([(val >> 8) & 0xff, val & 0xff]);
} else if (fc === 16) {
const n_val = val.length;
if (n_val > 127)
throw 'Number of data values exceeds limit (127)';
var n = 2*n_val + 3;
var reqd = Buffer.concat([Buffer.from([0, n_val, 2*n_val]), ...val.map(x => Buffer.from([(x >> 8) & 0xff, x & 0xff]))]);
} else
throw 'Function code not implemented';
// fill in message length
n += 4;
reqh[4] = (n >> 8) & 0xff;
reqh[5] = n & 0xff;
return Buffer.concat([reqh, reqd]);
```
It complains that n is already defined with at the 2nd "var n =" statement inside the else if (not true), complains @ fill in message length that n, reqh, and reqd are out of scope (not true, var is function scoped)
I've also used "== null" to test if something is null or undefined, and it gripes about how I need to use === to test against null. IMO it should say "be careful of the difference between == and ===" or something like that.
---
### Author:  [@knolleary](https://discourse.nodered.org/u/knolleary)
#### Post date: [24 August 2019 20:23 UTC](https://discourse.nodered.org/t/function-node-code-editor-warnings/14748/4 "2019-08-24T20:23:12Z")
`var` is function scoped and you have used `var n` twice in this function.... so the error message is correct.
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### Author:  [@thatcadguy](https://discourse.nodered.org/u/thatcadguy)
#### Post date: [24 August 2019 20:36 UTC](https://discourse.nodered.org/t/function-node-code-editor-warnings/14748/5 "2019-08-24T20:36:31Z")
The `var n`'s are in different branches of an if statement, only one will be executed.
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### Author:  [@knolleary](https://discourse.nodered.org/u/knolleary)
#### Post date: [24 August 2019 20:48 UTC](https://discourse.nodered.org/t/function-node-code-editor-warnings/14748/6 "2019-08-24T20:48:17Z")
Doesn't matter. They are in the same function so will both get hoisted to the start of the function.
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### Author:  [@thatcadguy](https://discourse.nodered.org/u/thatcadguy)
#### Post date: [24 August 2019 21:01 UTC](https://discourse.nodered.org/t/function-node-code-editor-warnings/14748/7 "2019-08-24T21:01:11Z")
Touché, it appears you are correct. Oh goody, yet another JS quirk...I assumed that it worked like C/C++.
---
### Author:  [@Steve-Mcl](https://discourse.nodered.org/u/Steve-Mcl)
#### Post date: [24 August 2019 21:03 UTC](https://discourse.nodered.org/t/function-node-code-editor-warnings/14748/8 "2019-08-24T21:03:47Z")
Never assume haha.
I mostly use `let` or `const` in block scope to avoid the side affects.