# How to declare and use the variable in Node-Red
**URL:** https://discourse.nodered.org/t/how-to-declare-and-use-the-variable-in-node-red/65030
**Category:** General
**Created:** [13 July 2022 06:16 UTC](https://discourse.nodered.org/t/how-to-declare-and-use-the-variable-in-node-red/65030 "2022-07-13T06:16:46Z")
**Posts on this page:** 4
**Page:** 1
### Author:  [@JackJackTan414](https://discourse.nodered.org/u/JackJackTan414)
#### Post date: [13 July 2022 06:16 UTC](https://discourse.nodered.org/t/how-to-declare-and-use-the-variable-in-node-red/65030/1 "2022-07-13T06:16:46Z")
Hi all , I am doing a simple test which consist of a button node to send the "msg.topic" to the function node when it is pressed via the dashboard UI. Code is shown in the first picture and the second picture shows the error warning when i try to deploy it. I am not sure if this format is correct to initialize the variable and get called when button is pressed.
I am planning to use this variable for the next function node. But first i have to make sure that this first function node is working.
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### Author:  [@bakman2](https://discourse.nodered.org/u/bakman2)
#### Post date: [13 July 2022 06:27 UTC](https://discourse.nodered.org/t/how-to-declare-and-use-the-variable-in-node-red/65030/2 "2022-07-13T06:27:28Z")
`a` should be a string (in this case)
`flow.set("a",1)`
`flow.get("a")` = 1
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### Author:  [@JackJackTan414](https://discourse.nodered.org/u/JackJackTan414)
#### Post date: [13 July 2022 06:53 UTC](https://discourse.nodered.org/t/how-to-declare-and-use-the-variable-in-node-red/65030/3 "2022-07-13T06:53:52Z")
got it! Thanks a lot!
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### Author:  [@system](https://discourse.nodered.org/u/system)
#### Post date: [27 July 2022 06:54 UTC](https://discourse.nodered.org/t/how-to-declare-and-use-the-variable-in-node-red/65030/4 "2022-07-27T06:54:39Z")
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