diff --git a/docs/index.json b/docs/index.json
index 6d1bb4f..60d5e32 100644
--- a/docs/index.json
+++ b/docs/index.json
@@ -4575,7 +4575,7 @@
   },
   {
     "kind": "packageJSON",
-    "content": "{\n  \"name\": \"indexedfts\",\n  \"version\": \"0.2.0\",\n  \"description\": \"Full-Text Search engine for web browser.\",\n  \"keywords\": [\n    \"fts\",\n    \"fulltext\",\n    \"full-text\",\n    \"indexeddb\",\n    \"database\",\n    \"client\"\n  ],\n  \"main\": \"dist/indexedfts\",\n  \"unpkg\": \"dist/indexedfts.min.js\",\n  \"scripts\": {\n    \"test\": \"npm run test:node && npm run test:browser\",\n    \"test:node\": \"NODE_ENV=development ./node_modules/.bin/nyc --require babel-core/register --reporter lcov ./node_modules/.bin/mocha --timeout 5000 ./test/node/*.js\",\n    \"test:browser\": \"NODE_ENV=development ./node_modules/.bin/karma start\",\n    \"build\": \"npm run docs && npm run benchmark:build && npm run dist:build\",\n    \"benchmark\": \"npm run benchmark:build && npm run benchmark:open\",\n    \"benchmark:build\": \"cd benchmark && ../node_modules/.bin/rollup -c\",\n    \"benchmark:open\": \"./node_modules/.bin/opener ./benchmark/index.html\",\n    \"dist:build\": \"NODE_ENV=production node build.js\",\n    \"docs\": \"./node_modules/.bin/esdoc\"\n  },\n  \"files\": [\n    \"README.md\",\n    \"dist\"\n  ],\n  \"repository\": {\n    \"type\": \"git\",\n    \"url\": \"git+https://github.com/macrat/indexedfts.git\"\n  },\n  \"author\": {\n    \"name\": \"MacRat\",\n    \"email\": \"m@crat.jp\",\n    \"url\": \"https://blanktar.jp/\"\n  },\n  \"license\": \"MIT\",\n  \"bugs\": \"https://github.com/macrat/indexedfts/issues\",\n  \"homepage\": \"https://macrat.github.io/indexedfts/\",\n  \"devDependencies\": {\n    \"asyncmark\": \"^0.2.1\",\n    \"babel-cli\": \"^6.26.0\",\n    \"babel-plugin-istanbul\": \"^4.1.6\",\n    \"babel-plugin-transform-runtime\": \"^6.23.0\",\n    \"babel-preset-env\": \"^1.6.1\",\n    \"babel-preset-power-assert\": \"^2.0.0\",\n    \"babelify\": \"^8.0.0\",\n    \"esdoc\": \"^1.0.4\",\n    \"esdoc-standard-plugin\": \"^1.0.0\",\n    \"fake-indexeddb\": \"^2.0.4\",\n    \"karma\": \"^2.0.0\",\n    \"karma-browserify\": \"^5.2.0\",\n    \"karma-chrome-launcher\": \"^2.2.0\",\n    \"karma-cli\": \"^1.0.1\",\n    \"karma-coverage\": \"^1.1.1\",\n    \"karma-firefox-launcher\": \"^1.1.0\",\n    \"karma-mocha\": \"^1.3.0\",\n    \"karma-mocha-reporter\": \"^2.2.5\",\n    \"mocha\": \"^5.0.4\",\n    \"nyc\": \"^11.5.0\",\n    \"opener\": \"^1.4.3\",\n    \"power-assert\": \"^1.4.4\",\n    \"promise-bench\": \"git+https://github.com/macrat/PromiseBench.git\",\n    \"rollup\": \"^0.55.5\",\n    \"rollup-plugin-babel\": \"^3.0.3\",\n    \"rollup-plugin-commonjs\": \"^8.4.1\",\n    \"rollup-plugin-node-resolve\": \"^3.2.0\",\n    \"rollup-plugin-uglify\": \"^3.0.0\"\n  },\n  \"babel\": {\n    \"env\": {\n      \"development\": {\n        \"presets\": [\n          \"env\",\n          \"power-assert\"\n        ],\n        \"plugins\": [\n          \"transform-runtime\"\n        ]\n      }\n    }\n  },\n  \"esdoc\": {\n    \"source\": \"./lib\",\n    \"destination\": \"./docs\",\n    \"plugins\": [\n      {\n        \"name\": \"esdoc-standard-plugin\"\n      }\n    ]\n  }\n}\n",
+    "content": "{\n  \"name\": \"indexedfts\",\n  \"version\": \"0.3.0\",\n  \"description\": \"Full-Text Search engine for web browser.\",\n  \"keywords\": [\n    \"fts\",\n    \"fulltext\",\n    \"full-text\",\n    \"indexeddb\",\n    \"database\",\n    \"client\"\n  ],\n  \"main\": \"dist/indexedfts\",\n  \"unpkg\": \"dist/indexedfts.min.js\",\n  \"scripts\": {\n    \"test\": \"npm run test:node && npm run test:browser\",\n    \"test:node\": \"NODE_ENV=development ./node_modules/.bin/nyc --require babel-core/register --reporter lcov ./node_modules/.bin/mocha --timeout 5000 ./test/node/*.js\",\n    \"test:browser\": \"NODE_ENV=development ./node_modules/.bin/karma start\",\n    \"build\": \"npm run docs && npm run benchmark:build && npm run dist:build\",\n    \"benchmark\": \"npm run benchmark:build && npm run benchmark:open\",\n    \"benchmark:build\": \"cd benchmark && ../node_modules/.bin/rollup -c\",\n    \"benchmark:open\": \"./node_modules/.bin/opener ./benchmark/index.html\",\n    \"dist:build\": \"NODE_ENV=production node build.js\",\n    \"docs\": \"./node_modules/.bin/esdoc\"\n  },\n  \"files\": [\n    \"README.md\",\n    \"dist\"\n  ],\n  \"repository\": {\n    \"type\": \"git\",\n    \"url\": \"git+https://github.com/macrat/indexedfts.git\"\n  },\n  \"author\": {\n    \"name\": \"MacRat\",\n    \"email\": \"m@crat.jp\",\n    \"url\": \"https://blanktar.jp/\"\n  },\n  \"license\": \"MIT\",\n  \"bugs\": \"https://github.com/macrat/indexedfts/issues\",\n  \"homepage\": \"https://macrat.github.io/indexedfts/\",\n  \"devDependencies\": {\n    \"asyncmark\": \"^0.2.1\",\n    \"babel-cli\": \"^6.26.0\",\n    \"babel-plugin-istanbul\": \"^4.1.6\",\n    \"babel-plugin-transform-runtime\": \"^6.23.0\",\n    \"babel-preset-env\": \"^1.6.1\",\n    \"babel-preset-power-assert\": \"^2.0.0\",\n    \"babelify\": \"^8.0.0\",\n    \"esdoc\": \"^1.0.4\",\n    \"esdoc-standard-plugin\": \"^1.0.0\",\n    \"fake-indexeddb\": \"^2.0.4\",\n    \"karma\": \"^2.0.0\",\n    \"karma-browserify\": \"^5.2.0\",\n    \"karma-chrome-launcher\": \"^2.2.0\",\n    \"karma-cli\": \"^1.0.1\",\n    \"karma-coverage\": \"^1.1.1\",\n    \"karma-firefox-launcher\": \"^1.1.0\",\n    \"karma-mocha\": \"^1.3.0\",\n    \"karma-mocha-reporter\": \"^2.2.5\",\n    \"mocha\": \"^5.0.4\",\n    \"nyc\": \"^11.5.0\",\n    \"opener\": \"^1.4.3\",\n    \"power-assert\": \"^1.4.4\",\n    \"promise-bench\": \"git+https://github.com/macrat/PromiseBench.git\",\n    \"rollup\": \"^0.55.5\",\n    \"rollup-plugin-babel\": \"^3.0.3\",\n    \"rollup-plugin-commonjs\": \"^8.4.1\",\n    \"rollup-plugin-node-resolve\": \"^3.2.0\",\n    \"rollup-plugin-uglify\": \"^3.0.0\"\n  },\n  \"babel\": {\n    \"env\": {\n      \"development\": {\n        \"presets\": [\n          \"env\",\n          \"power-assert\"\n        ],\n        \"plugins\": [\n          \"transform-runtime\"\n        ]\n      }\n    }\n  },\n  \"esdoc\": {\n    \"source\": \"./lib\",\n    \"destination\": \"./docs\",\n    \"plugins\": [\n      {\n        \"name\": \"esdoc-standard-plugin\"\n      }\n    ]\n  }\n}\n",
     "longname": "/home/ena/indexedfts/package.json",
     "name": "package.json",
     "static": true,
diff --git a/package-lock.json b/package-lock.json
index 762e3ac..de4e8c5 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -1,6 +1,6 @@
 {
   "name": "indexedfts",
-  "version": "0.2.0",
+  "version": "0.3.0",
   "lockfileVersion": 1,
   "requires": true,
   "dependencies": {
diff --git a/package.json b/package.json
index e8385b4..c656346 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "indexedfts",
-  "version": "0.2.0",
+  "version": "0.3.0",
   "description": "Full-Text Search engine for web browser.",
   "keywords": [
     "fts",