Define JavaScript runtimes semantic conventions (#2290)

CHANGELOG.md

@@ -33,6 +33,9 @@ release.
 
 ### Semantic Conventions
 
+- Define JavaScript runtime semantic conventions.
+  ([#2290](https://github.com/open-telemetry/opentelemetry-specification/pull/2290))
+
 ### Compatibility
 
 ### OpenTelemetry Protocol

specification/resource/semantic_conventions/process.md

@@ -131,16 +131,21 @@ Examples for some Java runtimes
 
 ### JavaScript runtimes
 
-TODO(<https://github.com/open-telemetry/opentelemetry-js/issues/1544>): Confirm the contents here
+JavaScript instrumentation should fill in the values by copying from built-in runtime constants.
 
-| Value | Description |
-| --- | --- |
-| `nodejs` | NodeJS |
-| `browser` | Web Browser |
-| `iojs` | io.js |
-| `graalvm` | GraalVM |
+- `process.runtime.name`:
+  - When the runtime is Node.js, fill in the constant value `nodejs`.
+  - When the runtime is Web Browser, fill in the constant value `browser`.
+- `process.runtime.version`:
+  - When the runtime is Node.js, fill in the value of `process.versions.node`.
+  - When the runtime is Web Browser, fill in the value of `navigator.userAgent`.
 
-When the value is `browser`, `process.runtime.version` SHOULD be set to the User-Agent header.
+Examples for some JavaScript runtimes
+
+| Name | `process.runtime.name` | `process.runtime.version` |
+| --- | --- | --- |
+| Node.js | nodejs | 14.15.4 |
+| Web Browser | browser | Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/97.0.4692.71 Safari/537.36 |
 
 ### .NET Runtimes