tessl/npm-expo--config

A library for interacting with the app.json configuration files in Expo projects

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SDK Version Resolution

Name: tessl/npm-expo--config
Author: tessl

Automatic detection and validation of Expo SDK versions from configuration files or installed packages, ensuring compatibility and proper versioning.

Capabilities

SDK Version Detection

Resolve the Expo SDK version for a project from configuration or installed packages.

/**
 * Resolve the Expo SDK Version from input config or installed expo package
 * First checks the provided config, then falls back to package version detection
 * @param projectRoot - Project root directory
 * @param exp - Optional config object with sdkVersion
 * @returns SDK version string (e.g., "51.0.0")
 * @throws ConfigError if expo package not found or invalid
 */
function getExpoSDKVersion(
  projectRoot: string,
  exp?: Pick<ExpoConfig, 'sdkVersion'>
): string;

Usage Examples:

import { getExpoSDKVersion } from "@expo/config";

// Get SDK version from project
const sdkVersion = getExpoSDKVersion("/path/to/expo-project");
// Result: "51.0.0" (from installed expo package or config)

// Use specific config
const configWithSDK = { sdkVersion: "50.0.0" };
const specifiedVersion = getExpoSDKVersion("/path/to/project", configWithSDK);
// Result: "50.0.0" (uses provided version)

// Auto-detect from installed expo package
const autoVersion = getExpoSDKVersion("/path/to/project", {});
// Reads from node_modules/expo/package.json

SDK Version Resolution Logic

The SDK version resolution follows this priority order:

Explicit Configuration: If exp.sdkVersion is provided, use it directly
Package Detection: Read version from installed expo package
Version Normalization: Convert package version to SDK version format

Package Version to SDK Version Mapping

The function converts npm package versions to SDK versions:

Package version 51.0.15 → SDK version 51.0.0
Package version 50.1.2 → SDK version 50.0.0
Package version 49.0.21 → SDK version 49.0.0

The major version number is preserved, while minor and patch are normalized to .0.0.

Error Handling

SDK version resolution may fail with specific error conditions:

// Thrown when expo package is not installed
throw new ConfigError(
  "Cannot determine the project's Expo SDK version because the module `expo` is not installed. Install it with `npm install expo` and try again.",
  'MODULE_NOT_FOUND'
);

// Thrown when expo package.json is invalid
throw new ConfigError(
  "Cannot determine the project's Expo SDK version because the module `expo` has an invalid package.json (missing `version` field). Try reinstalling node modules and trying again.",
  'MODULE_NOT_FOUND'
);

Error Handling Examples:

import { getExpoSDKVersion, ConfigError } from "@expo/config";

try {
  const sdkVersion = getExpoSDKVersion("/path/to/project");
  console.log("SDK Version:", sdkVersion);
} catch (error) {
  if (error instanceof ConfigError) {
    switch (error.code) {
      case 'MODULE_NOT_FOUND':
        console.log("Please install expo: npm install expo");
        break;
      default:
        console.log("Configuration error:", error.message);
    }
  }
}

Integration with Configuration

SDK version resolution is automatically integrated into the main configuration system:

import { getConfig } from "@expo/config";

// SDK version is automatically resolved and included
const config = getConfig("/path/to/project");
console.log("Auto-resolved SDK:", config.exp.sdkVersion);

// Skip SDK version validation for incomplete projects
const configNoSDK = getConfig("/path/to/project", {
  skipSDKVersionRequirement: true
});
// Won't throw if expo package missing

SDK Version Types

// Part of ExpoConfig interface
interface ExpoConfig {
  /** Expo SDK version (e.g., "51.0.0", "UNVERSIONED") */
  sdkVersion?: string;
  // ... other config properties
}

// Error codes related to SDK version resolution
type ConfigErrorCode = 
  | 'MODULE_NOT_FOUND'  // expo package not found
  | 'INVALID_CONFIG'    // invalid package.json
  // ... other error codes