v2: prepare to move

v2/lib/load/config.js

@@ -0,0 +1,67 @@
+const fs = require('fs-extra');
+const path = require('path');
+
+module.exports = function loadConfig(siteDir, deleteCache = true) {
+  const configPath = path.resolve(siteDir, 'siteConfig.js');
+  if (deleteCache) {
+    delete require.cache[configPath];
+  }
+  let config = {};
+  if (fs.existsSync(configPath)) {
+    config = require(configPath); // eslint-disable-line
+  }
+
+  const requiredFields = [
+    'title',
+    'tagline',
+    'organizationName',
+    'projectName',
+    'baseUrl'
+  ];
+  const optionalFields = [
+    'customDocsPath',
+    'defaultLanguage',
+    'highlight',
+    'markdownPlugins',
+    'configureWebpack',
+    'chainWebpack',
+    'docsUrl',
+    'customFields'
+  ];
+  const missingFields = requiredFields.filter(field => !config[field]);
+  if (missingFields && missingFields.length > 0) {
+    throw new Error(
+      `${missingFields.join(', ')} fields are missing in siteConfig.js`
+    );
+  }
+
+  /* Fill default value */
+  const defaultConfig = {
+    customDocsPath: 'docs',
+    docsUrl: 'docs'
+  };
+  Object.keys(defaultConfig).forEach(field => {
+    if (!config[field]) {
+      config[field] = defaultConfig[field];
+    }
+  });
+
+  /* 
+    User's own array of custom fields, 
+    e.g: if they want to include some field so they can access it later from `props.siteConfig`
+  */
+  const {customFields = []} = config;
+
+  /* We don't allow useless/ not meaningful field */
+  const allowedFields = [...requiredFields, ...optionalFields, ...customFields];
+  const uselessFields = Object.keys(config).filter(
+    field => !allowedFields.includes(field)
+  );
+  if (uselessFields && uselessFields.length > 0) {
+    throw new Error(
+      `${uselessFields.join(', ')} fields are useless in siteConfig.js`
+    );
+  }
+
+  return config;
+};