# Developing Nodes

**URL:** https://discourse.nodered.org/c/developing-nodes/15.md?page=34

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**Page:** 35

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## [Message Datagram with fixed length, padding texts](https://discourse.nodered.org/t/message-datagram-with-fixed-length-padding-texts/40326)

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**Author:** [@wvsbsp](https://discourse.nodered.org/u/wvsbsp)\
**Replies:** 1\
**Last updated:** [3 February 2021 19:57 UTC](https://discourse.nodered.org/t/message-datagram-with-fixed-length-padding-texts/40326 "2021-02-03T19:57:09Z")

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I try to create a datagram that contains variable texts. The datagram has fixed lenght for the texts, so i need ti add trailing blanks to the datagram. unfortunately, JavaScript automaticalls removes trailing blanks and…

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## [Getting Continuous Output from Python Script in Node-RED](https://discourse.nodered.org/t/getting-continuous-output-from-python-script-in-node-red/40327)

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**Author:** [@hkayan](https://discourse.nodered.org/u/hkayan)\
**Replies:** 2\
**Last updated:** [3 February 2021 18:59 UTC](https://discourse.nodered.org/t/getting-continuous-output-from-python-script-in-node-red/40327 "2021-02-03T18:59:59Z")

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Hello, Sorry the question might be so trivial, but I could not make it work, and I am not getting any errors, so couldn't fix the issue. I have a python3 script located at /home/pi/Zigbee\_v1.py. The script gets data fr…

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## [Problems with npm publish, why is my node spam?](https://discourse.nodered.org/t/problems-with-npm-publish-why-is-my-node-spam/40229)

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**Author:** [@iiot2k](https://discourse.nodered.org/u/iiot2k)\
**Replies:** 5\
**Last updated:** [2 February 2021 15:49 UTC](https://discourse.nodered.org/t/problems-with-npm-publish-why-is-my-node-spam/40229 "2021-02-02T15:49:39Z")

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Hi, I write lot of nodes for Node-Red . Since 2 days I want put this nodes to npm with npm publish. Every time I become following error: 403 Forbidden - PUT https://registry.npmjs.org/node-red-contrib-xxxx - Package …

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## [Message sends old object](https://discourse.nodered.org/t/message-sends-old-object/40210)

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**Author:** [@jeevan900929](https://discourse.nodered.org/u/jeevan900929)\
**Replies:** 4\
**Last updated:** [2 February 2021 08:20 UTC](https://discourse.nodered.org/t/message-sends-old-object/40210 "2021-02-02T08:20:37Z")

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I have created a node, and within it there is a for loop: https://monosnap.com/file/DPbBhDwZe2cnPglIWujIrVTr5s3eJV Somehow, all the messages in the for loop gets set to the last iteration's message: https://monosnap.c…

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## [How do we create a Node from an RxJs Observable?](https://discourse.nodered.org/t/how-do-we-create-a-node-from-an-rxjs-observable/40154)

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**Author:** [@jeevan900929](https://discourse.nodered.org/u/jeevan900929)\
**Replies:** 3\
**Last updated:** [2 February 2021 08:09 UTC](https://discourse.nodered.org/t/how-do-we-create-a-node-from-an-rxjs-observable/40154 "2021-02-02T08:09:43Z")

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Is there a way to emit a message stream in a node by subscribing to an Observable?

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## [How to sort node menu](https://discourse.nodered.org/t/how-to-sort-node-menu/40213)

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**Author:** [@jiuxiao\_chen](https://discourse.nodered.org/u/jiuxiao_chen)\
**Replies:** 2\
**Last updated:** [2 February 2021 07:17 UTC](https://discourse.nodered.org/t/how-to-sort-node-menu/40213 "2021-02-02T07:17:29Z")

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hi, I have customized a node list, Enerwise Connect. Can I put it on the top? Not the bottom .

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## [Beginner suport function problem](https://discourse.nodered.org/t/beginner-suport-function-problem/40177)

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**Author:** [@shaodw31](https://discourse.nodered.org/u/shaodw31)\
**Replies:** 4\
**Last updated:** [1 February 2021 18:03 UTC](https://discourse.nodered.org/t/beginner-suport-function-problem/40177 "2021-02-01T18:03:29Z")

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hello everyone, i´m new here and didn´t have a lot of experince with node red. i use it to visualice parameters from my heating system. i get this informations by a web request. more or less it works, but i have an i…

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## [Testing: assert a message is not sent](https://discourse.nodered.org/t/testing-assert-a-message-is-not-sent/40160)

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**Author:** [@sander76](https://discourse.nodered.org/u/sander76)\
**Replies:** 0\
**Last updated:** [1 February 2021 10:40 UTC](https://discourse.nodered.org/t/testing-assert-a-message-is-not-sent/40160 "2021-02-01T10:40:14Z")

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Starting to learn creating nodes and testing them using the node-red-test-helper module. (coming from python) I have a node with multiple outputs. Based on a certain input I want to test whether certain outputs are send…

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## [Ten IPCam OSD / overlay text](https://discourse.nodered.org/t/ten-ipcam-osd-overlay-text/40071)

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**Author:** [@Muhonen](https://discourse.nodered.org/u/Muhonen)\
**Replies:** 0\
**Last updated:** [30 January 2021 20:55 UTC](https://discourse.nodered.org/t/ten-ipcam-osd-overlay-text/40071 "2021-01-30T20:55:04Z")

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Ten IPCam OSD / overlay text test dahua, hikvision, foscam milesight, fisheye, hd megapixel, floureon, etc... \[{"id":"4a861abf.3250cc","type":"tab","label":"IPCam OSD text overlay test","disabled":false,"info":""},{"id…

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## [Presence sensor booleans](https://discourse.nodered.org/t/presence-sensor-booleans/39969)

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**Author:** [@elder1104](https://discourse.nodered.org/u/elder1104)\
**Replies:** 3\
**Last updated:** [29 January 2021 16:49 UTC](https://discourse.nodered.org/t/presence-sensor-booleans/39969 "2021-01-29T16:49:33Z")

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Hello, I am a total newbie and just started using home assistant and node red. I am trying to get some booleans going were if at least one person home the home boolean is toggled on, and if no one is home toggle off the…

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## [Configuring Serial Node for Bluetooth Communication](https://discourse.nodered.org/t/configuring-serial-node-for-bluetooth-communication/39943)

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**Author:** [@hkayan](https://discourse.nodered.org/u/hkayan)\
**Replies:** 9\
**Last updated:** [29 January 2021 11:48 UTC](https://discourse.nodered.org/t/configuring-serial-node-for-bluetooth-communication/39943 "2021-01-29T11:48:31Z")

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Hello, I am connecting Arduino to Rapberry Pi over bluetooth. On Raspberry Pi if I create rfcomm channel via sudo rfcomm hci0 MAC\_HERE 1, I can use serial input node in Node-RED and get data as /dev/rfcomm0 appears whe…

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## [Function with 2 Output](https://discourse.nodered.org/t/function-with-2-output/39986)

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**Author:** [@bsailer1975](https://discourse.nodered.org/u/bsailer1975)\
**Replies:** 1\
**Last updated:** [29 January 2021 07:32 UTC](https://discourse.nodered.org/t/function-with-2-output/39986 "2021-01-29T07:32:24Z")

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Good morning! Has anyone an idea why i dont get any output on channel 2 of the "Action after... - function"?

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## [Balboa Whirlpool](https://discourse.nodered.org/t/balboa-whirlpool/39930)

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**Author:** [@nuiler](https://discourse.nodered.org/u/nuiler)\
**Replies:** 0\
**Last updated:** [28 January 2021 14:30 UTC](https://discourse.nodered.org/t/balboa-whirlpool/39930 "2021-01-28T14:30:43Z")

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I found an interesting node. Unfortunately it doesn't work when I want to issue a command. It comes on the debug node TypeError: Cannot read property 'crc' of undefined Somehow it is due to the function node "turn o…

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## [Node-red and air purifier 3h](https://discourse.nodered.org/t/node-red-and-air-purifier-3h/39889)

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**Author:** [@arybek](https://discourse.nodered.org/u/arybek)\
**Replies:** 0\
**Last updated:** [27 January 2021 18:21 UTC](https://discourse.nodered.org/t/node-red-and-air-purifier-3h/39889 "2021-01-27T18:21:34Z")

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For several days I have been trying to program mi air purifier 3h in node-red. Almost everything works, the only annoying thing is that every minute the device beeps and sets the fan speed to the same - the check conditi…

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## [Help with making a volume gui widget with no html knowledge](https://discourse.nodered.org/t/help-with-making-a-volume-gui-widget-with-no-html-knowledge/38494)

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**Author:** [@9toejack](https://discourse.nodered.org/u/9toejack)\
**Replies:** 25\
**Last updated:** [27 January 2021 07:17 UTC](https://discourse.nodered.org/t/help-with-making-a-volume-gui-widget-with-no-html-knowledge/38494 "2021-01-27T07:17:46Z")

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Hello, i am totally new and learning node-red. i have no programing exp. nor html exp. I'm learning stuff on the fly. so with that any help i can get with my project will be appreciated. however i am not asking for s…

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## [Hikvision OSD / overlay text](https://discourse.nodered.org/t/hikvision-osd-overlay-text/39783)

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**Author:** [@Muhonen](https://discourse.nodered.org/u/Muhonen)\
**Replies:** 3\
**Last updated:** [26 January 2021 16:10 UTC](https://discourse.nodered.org/t/hikvision-osd-overlay-text/39783 "2021-01-26T16:10:10Z")

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domoticz / out retrieves temperature information and sends it to the camera as osd text \[{"id":"e6698485.8469d","type":"tab","label":"Hikvision OK","disabled":false,"info":""},{"id":"3af0aa23.575896","type":"http reques…

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## [Dahua OSD / overlay text](https://discourse.nodered.org/t/dahua-osd-overlay-text/39652)

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**Author:** [@Muhonen](https://discourse.nodered.org/u/Muhonen)\
**Replies:** 3\
**Last updated:** [26 January 2021 15:28 UTC](https://discourse.nodered.org/t/dahua-osd-overlay-text/39652 "2021-01-26T15:28:02Z")

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I'll try to get nodered to write the temperature on the display of the camera Dahua, Hikvision and Camhi I've got to work but dahualla a problem. The name can be changed from the trigger, but I can't get the temperature…

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## [Custom node require failure](https://discourse.nodered.org/t/custom-node-require-failure/39772)

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**Author:** [@UnivSim](https://discourse.nodered.org/u/UnivSim)\
**Replies:** 3\
**Last updated:** [26 January 2021 13:08 UTC](https://discourse.nodered.org/t/custom-node-require-failure/39772 "2021-01-26T13:08:38Z")

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Hi, I'm writing a custom node for Node-red (see versions below) but i require other modules/scripts in it. When i add the require line (see my code) it failes to show up in the node-red brwoser interface. when i commen…

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## [Communication between Node and Config Node](https://discourse.nodered.org/t/communication-between-node-and-config-node/8926)

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**Author:** [@Devbrat](https://discourse.nodered.org/u/Devbrat)\
**Replies:** 8\
**Last updated:** [22 January 2021 14:56 UTC](https://discourse.nodered.org/t/communication-between-node-and-config-node/8926 "2021-01-22T14:56:00Z")

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I want to send one input value of Config Node to some other Node which is using that config node. Is there any way to have communication between both Node?

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## [Custom Nodes UI styling](https://discourse.nodered.org/t/custom-nodes-ui-styling/39502)

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**Author:** [@jpinto](https://discourse.nodered.org/u/jpinto)\
**Replies:** 1\
**Last updated:** [21 January 2021 14:44 UTC](https://discourse.nodered.org/t/custom-nodes-ui-styling/39502 "2021-01-21T14:44:15Z")

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Hey all, I developed some nodes, and when user drag and drop in the workspace I want to make some changes to the DOM(Svg) of the dragged node. There is any kind of event that i can register to make such a feature? Chee…

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## [Testing a node, where is the error output?](https://discourse.nodered.org/t/testing-a-node-where-is-the-error-output/39371)

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**Author:** [@sander76](https://discourse.nodered.org/u/sander76)\
**Replies:** 2\
**Last updated:** [20 January 2021 19:55 UTC](https://discourse.nodered.org/t/testing-a-node-where-is-the-error-output/39371 "2021-01-20T19:55:54Z")

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Getting started with testing my created Node (coming from Python). I have followed the testing tutorial (https://nodered.org/docs/creating-nodes/first-node#unit-testing) and got it working. However, I now have a test th…

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## [Creating your own nodes for Node-RED](https://discourse.nodered.org/t/creating-your-own-nodes-for-node-red/39195)

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**Author:** [@Mas](https://discourse.nodered.org/u/Mas)\
**Replies:** 9\
**Last updated:** [19 January 2021 19:33 UTC](https://discourse.nodered.org/t/creating-your-own-nodes-for-node-red/39195 "2021-01-19T19:33:34Z")

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Hi, I am new to using Node-red. I need to create my own node in node-red. could you please help me to do this? Regards

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## [httpNode endpoint - how to "remove"](https://discourse.nodered.org/t/httpnode-endpoint-how-to-remove/38995)

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**Author:** [@hklages](https://discourse.nodered.org/u/hklages)\
**Replies:** 1\
**Last updated:** [18 January 2021 13:16 UTC](https://discourse.nodered.org/t/httpnode-endpoint-how-to-remove/38995 "2021-01-18T13:16:43Z")

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The RED.httpNode.get works fine and I can register a new endpoint. 2021-01-18 update: Questions How can I remove that endpoint? Is there anywhere a list what endpoints are already defined? What happens if an endpoint…

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## [Custom node / function node - single instance](https://discourse.nodered.org/t/custom-node-function-node-single-instance/38992)

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**Author:** [@hklages](https://discourse.nodered.org/u/hklages)\
**Replies:** 6\
**Last updated:** [18 January 2021 08:25 UTC](https://discourse.nodered.org/t/custom-node-function-node-single-instance/38992 "2021-01-18T08:25:55Z")

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How can I prevent user to create multiple config nodes / function nodes?

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## [Help with Dimmer function](https://discourse.nodered.org/t/help-with-dimmer-function/39264)

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**Author:** [@benilsson](https://discourse.nodered.org/u/benilsson)\
**Replies:** 0\
**Last updated:** [17 January 2021 12:55 UTC](https://discourse.nodered.org/t/help-with-dimmer-function/39264 "2021-01-17T12:55:47Z")

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Hi Can someone help me to write this. I have Shelly Dimmer 2 Home assistant with node red on a raspberry Lights thru Deconz I want to use input 2 on the Shelly Dimmer to on/off/dimming a light in Deconz. On input 2…

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## [Utilsation switch](https://discourse.nodered.org/t/utilsation-switch/39217)

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**Author:** [@yan](https://discourse.nodered.org/u/yan)\
**Replies:** 1\
**Last updated:** [17 January 2021 04:56 UTC](https://discourse.nodered.org/t/utilsation-switch/39217 "2021-01-17T04:56:37Z")

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Bonjour. je souhait utilisee la fonction "Switch" pour mettre en route des relais. hors j'active 0 bien les relais mais je voudrais que quand la variable ne plus la bonne revenir a le etat 1 comment faire ?

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## [Does the node-red-test-helper support multiple outputs?](https://discourse.nodered.org/t/does-the-node-red-test-helper-support-multiple-outputs/19997)

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**Author:** [@kareem613](https://discourse.nodered.org/u/kareem613)\
**Replies:** 6\
**Last updated:** [15 January 2021 22:48 UTC](https://discourse.nodered.org/t/does-the-node-red-test-helper-support-multiple-outputs/19997 "2021-01-15T22:48:54Z")

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I've got the hang of writing unit tests in mocha using the test helper. It's great. I'm trying to figure out to test an output on a second output of a node. Is this supported by the test helper?

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## [Full semver comparison of module versions and private registry](https://discourse.nodered.org/t/full-semver-comparison-of-module-versions-and-private-registry/39177)

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**Author:** [@HaKr](https://discourse.nodered.org/u/HaKr)\
**Replies:** 2\
**Last updated:** [15 January 2021 16:05 UTC](https://discourse.nodered.org/t/full-semver-comparison-of-module-versions-and-private-registry/39177 "2021-01-15T16:05:41Z")

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We are developing a module with fourteen nodes, which we want to share with our QA colleagues through an in-company package repository before publishing them to NPM. We also provide a catalog.json file with the relevant …

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## [How to access environment variables in HTML of custom node](https://discourse.nodered.org/t/how-to-access-environment-variables-in-html-of-custom-node/39086)

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**Author:** [@BShashwat](https://discourse.nodered.org/u/BShashwat)\
**Replies:** 3\
**Last updated:** [15 January 2021 13:51 UTC](https://discourse.nodered.org/t/how-to-access-environment-variables-in-html-of-custom-node/39086 "2021-01-15T13:51:57Z")

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Hi, How can I access environment variables which are being passed to Node red docker container via. shell script, in the HTML file of a custom node. In HTML file I need to make Ajax calls to get data from API that will …

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## [Best practice for use of Done and Error](https://discourse.nodered.org/t/best-practice-for-use-of-done-and-error/39063)

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**Author:** [@Colin](https://discourse.nodered.org/u/Colin)\
**Replies:** 8\
**Last updated:** [13 January 2021 17:34 UTC](https://discourse.nodered.org/t/best-practice-for-use-of-done-and-error/39063 "2021-01-13T17:34:19Z")

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Is there a best practice recommendation for the use of done() and error() in contrib nodes? I notice that the email node calls done() or error() when it is finished (as picked up by Complete and Catch nodes) but never b…

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