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Node.js Runtime¶

This reference describes Node.js runtime support, worker settings, and dependency practices for Azure Functions apps using the v4 programming model.

Main Content¶

flowchart LR
    A[Node 18 LTS] --> D[Supported]
    B[Node 20 LTS] --> D
    C[Node 22 Current] --> D
    D --> E[Functions runtime v4]

Supported Node.js Versions¶

Node.js Version	Status	Recommendation
18	LTS	Use for legacy compatibility windows
20	LTS	Default choice for new production apps
22	Current	Use after dependency compatibility checks

Core Runtime Settings¶

Setting	Purpose	Example
`FUNCTIONS_WORKER_RUNTIME`	Select Node worker	`node`
`WEBSITE_NODE_DEFAULT_VERSION`	Node version on Windows workers only	`~20`
`siteConfig.linuxFxVersion`	Node runtime stack on Linux workers	`Node\|20`
`languageWorkers__node__arguments`	Node process arguments	`--max-old-space-size=4096`
`FUNCTIONS_EXTENSION_VERSION`	Functions runtime line	`~4`

Set runtime version and app settings¶

az functionapp config appsettings set --name $APP_NAME --resource-group $RG --settings "FUNCTIONS_WORKER_RUNTIME=node" "FUNCTIONS_EXTENSION_VERSION=~4" "WEBSITE_NODE_DEFAULT_VERSION=~20" "languageWorkers__node__arguments=--max-old-space-size=4096"
az functionapp config appsettings set --name $APP_NAME --resource-group $RG --settings "FUNCTIONS_WORKER_RUNTIME=node" "FUNCTIONS_EXTENSION_VERSION=~4" "languageWorkers__node__arguments=--max-old-space-size=4096"
az functionapp config set --name $APP_NAME --resource-group $RG --linux-fx-version "Node|20"

Windows apps: set WEBSITE_NODE_DEFAULT_VERSION=~20.
Linux apps: set runtime via linuxFxVersion (Node|20).

Memory and Heap Guidance¶

Increase languageWorkers__node__arguments for memory-heavy workloads.
Keep bundle size and dependency graph small to reduce cold start.
Reuse clients across invocations to reduce connection churn.

Dependency Management¶

Use @azure/functions package for v4 APIs.
Pin major versions in package.json.
Prefer remote build for Linux deployments when native packages are used.

{
  "name": "node-func-app",
  "version": "1.0.0",
  "main": "src/functions/httpTrigger.js",
  "dependencies": {
    "@azure/functions": "^4.5.0",
    "@azure/identity": "^4.4.1",
    "@azure/storage-blob": "^12.24.0"
  }
}

See Also¶

Sources¶