# This.context() VS this.context().flow in custom node

**URL:** <https://discourse.nodered.org/t/this-context-vs-this-context-flow-in-custom-node/87320>\
**Category:** Developing Nodes\
**Created:** [18 April 2024 19:34 UTC](https://discourse.nodered.org/t/this-context-vs-this-context-flow-in-custom-node/87320 "2024-04-18T19:34:15Z")\
**Posts on this page:** 6\
**Page:** 1

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**Author:** ![NILD](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/nild/32/90290_2.png) [@NILD](https://discourse.nodered.org/u/NILD)\
**Post date:** [18 April 2024 19:34 UTC](https://discourse.nodered.org/t/this-context-vs-this-context-flow-in-custom-node/87320/1 "2024-04-18T19:34:15Z")

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Hi,

I would appreciate it if you could review the code at this link:

> <https://github.com/NILD01/node-red-contrib-operatelogic/blob/main/OperateLogic.js>

In line 15, I have to use `this.context().flow` instead of `this.context()` for the code to function correctly. When I use `this.context()`, I’ve noticed that the code sometimes executes `node.status({ fill: "blue", shape: "dot", text: "waiting for trigger" })` (found in line 24), on unexpected moments. However, when I use `this.context().flow`, it only executes after the first deployment, as I would expect.

This is my first node and many things are new to me.  
So it might be a silly question, but I really want to know why i can't use this.context() in my code.

Thank you in advance.

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**Author:** ![marcus-j-davies](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/marcus-j-davies/32/103435_2.png) [@marcus-j-davies](https://discourse.nodered.org/u/marcus-j-davies)\
**Post date:** [18 April 2024 20:11 UTC](https://discourse.nodered.org/t/this-context-vs-this-context-flow-in-custom-node/87320/2 "2024-04-18T20:11:31Z")

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Hi @NILD

I have moved this to **Developing Nodes** - and its great to hear, another contributor is adding to the cause!

A few Pointers....

During the init phase (`OperateLogicNode`) I wouldn't attempt to output anything (Line : 23)

Why?  
Node RED is still getting it's S\*\*t together about this node during this phase, if you need to output anything at this early boot stage, add a delay (`setTimeout`)

This may extend to `status` I'm not entirely sure.

as for context.

- `this.context()` - The nodes own context
- `this.context().flow` - The context of the flow that the node lives (you **cant** use this for config nodes)
- `this.context().global` - The global context

`var` VS, `let` VS `const`

Use `const` if the value never changes... BUT a mutable `object` still never changes its pointer, so still use `const` for these.

Use `let` not `var` if the value changes.

`var` can be (and is) troublesome in todays javascript estate

I know its not a direct answer, but some of the above, may leave a few bread crumbs.  
My advice will be, if you are attaching to significant areas during the init phase, add a small delay with `setTimeout`

And Welcome to the Forums 😄

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**Author:** ![NILD](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/nild/32/90290_2.png) [@NILD](https://discourse.nodered.org/u/NILD)\
**Post date:** [19 April 2024 08:16 UTC](https://discourse.nodered.org/t/this-context-vs-this-context-flow-in-custom-node/87320/3 "2024-04-19T08:16:08Z")

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Thank you for quick response. I will change the code to your pointers.

I have conducted further tests comparing `this.context()` and `this.context().flow`. The differences (and probems i have) between the two are now somewhat clearer. When I use `this.context().flow`, I can freely restart Node-RED or alter the node settings, and it will still function correctly. It retains its state.

However, if I switch the code to `this.context()` and perform the same actions, it seems as if its previous state is lost and it does not operate as anticipated.

There must be something that i've missed.

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**Author:** ![NILD](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/nild/32/90290_2.png) [@NILD](https://discourse.nodered.org/u/NILD)\
**Post date:** [19 April 2024 15:19 UTC](https://discourse.nodered.org/t/this-context-vs-this-context-flow-in-custom-node/87320/4 "2024-04-19T15:19:07Z")

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I found the cause.  
I didn't realise that on my test system the contextstorage in settings.js was disabled.😮‍💨

So when i use this.context();flow it seems it stores the data over restarts of the flows?

New question:  
Can i rely on this setting for developing nodes?

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**Author:** ![knolleary](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/knolleary/32/3_2.png) [@knolleary](https://discourse.nodered.org/u/knolleary)\
**Post date:** [19 April 2024 15:43 UTC](https://discourse.nodered.org/t/this-context-vs-this-context-flow-in-custom-node/87320/5 "2024-04-19T15:43:49Z")

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> [@NILD](#):
>
> Can i rely on this setting for developing nodes?

It depends what you mean by that. Each individual user will choose whether they have persistent context enabled or not - that is not something your node can enforce.

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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:** [18 July 2024 15:44 UTC](https://discourse.nodered.org/t/this-context-vs-this-context-flow-in-custom-node/87320/6 "2024-07-18T15:44:22Z")

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