runtime-env

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gen-js ​

gen-js generates browser runtime config JavaScript.

Command syntax ​

bash
runtime-env [top-level options] gen-js [command options]

Top-level options and ordering ​

Top-level options are passed before the subcommand and affect gen-js behavior:

  • --schema-file <path>: choose schema source.
  • --global-variable-name <name>: controls generated global object name.
  • --watch: rerun generation when watched inputs change.

gen-js command options ​

  • --output-file <path>: write generated JS to a file.
  • --env-file <path>: load env values from one or more env files.

Default behavior ​

  • --schema-file default: .runtimeenvschema.json
  • --global-variable-name default: runtimeEnv
  • --watch default: off
  • if --env-file is omitted: values come from the current process environment
  • if --output-file is omitted: output is written to stdout
  • if both env files and process environment are used: process environment wins

gen-js is useful for development, staging, deployment/runtime, and other custom workflows.

Nested JSON example ​

Schema:

json
{
  "type": "object",
  "properties": {
    "FEATURE_FLAGS": {
      "type": "object",
      "properties": {
        "betaCheckout": { "type": "boolean" }
      },
      "required": ["betaCheckout"]
    }
  },
  "required": ["FEATURE_FLAGS"]
}

Env value:

bash
FEATURE_FLAGS={"betaCheckout":true}

Example ​

Stage-specific API URL generated for a local/staging workflow:

bash
runtime-env --schema-file .runtimeenvschema.json gen-js --env-file .env.staging --output-file ./public/runtime/runtime-env.js