diff --git a/.editorconfig b/.editorconfig
new file mode 100644
index 00000000..4039ff11
--- /dev/null
+++ b/.editorconfig
@@ -0,0 +1,12 @@
+root = true
+
+[*]
+charset = utf-8
+end_of_line = lf
+indent_size = 2
+indent_style = space
+insert_final_newline = true
+trim_trailing_whitespace = true
+
+[*.md]
+trim_trailing_whitespace = false
diff --git a/.eslintrc b/.eslintrc
new file mode 100644
index 00000000..ac6ca880
--- /dev/null
+++ b/.eslintrc
@@ -0,0 +1,21 @@
+{
+  "overrides": [
+    {
+      "files": "*.ts",
+      "parser": "@typescript-eslint/parser",
+      "rules": {
+        "no-unused-vars": "off",
+        "no-useless-constructor": "off",
+        "@typescript-eslint/no-unused-vars": "error",
+        "@typescript-eslint/no-useless-constructor": "error"
+      }
+    }
+  ],
+  "parserOptions": {
+    "ecmaVersion": 2018,
+    "sourceType": "module"
+  },
+  "plugins": [
+    "@typescript-eslint/eslint-plugin"
+  ]
+}
diff --git a/.gitignore b/.gitignore
index a7502d1d..791cb484 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,4 +1,5 @@
 .idea
+build/
 .nyc_output
 node_modules
 .DS_Store
diff --git a/.mocharc.json b/.mocharc.json
new file mode 100644
index 00000000..ef1c3645
--- /dev/null
+++ b/.mocharc.json
@@ -0,0 +1,6 @@
+{
+  "spec": [
+    "build/test",
+    "test"
+  ]
+}
diff --git a/.nycrc b/.nycrc
new file mode 100644
index 00000000..89f6c3a0
--- /dev/null
+++ b/.nycrc
@@ -0,0 +1,13 @@
+{
+  "exclude": [
+    "build/test/**",
+    "test/**"
+  ],
+  "reporter": [
+    "html",
+    "text"
+  ],
+  "lines": 100,
+  "branches": "97",
+  "statements": "100"
+}
diff --git a/index.js b/index.js
index 24962d66..4522fcc1 100644
--- a/index.js
+++ b/index.js
@@ -1,7 +1,7 @@
 const camelCase = require('camelcase')
 const decamelize = require('decamelize')
 const path = require('path')
-const tokenizeArgString = require('./lib/tokenize-arg-string')
+const { tokenizeArgString } = require('./build/lib/tokenize-arg-string')
 const util = require('util')
 
 // See https://github.com/yargs/yargs-parser#supported-nodejs-versions for our
diff --git a/lib/tokenize-arg-string.js b/lib/tokenize-arg-string.ts
similarity index 78%
rename from lib/tokenize-arg-string.js
rename to lib/tokenize-arg-string.ts
index 260c67c1..52827080 100644
--- a/lib/tokenize-arg-string.js
+++ b/lib/tokenize-arg-string.ts
@@ -1,5 +1,5 @@
 // take an un-split argv string and tokenize it.
-module.exports = function (argString) {
+export function tokenizeArgString (argString: string | any[]): string[] {
   if (Array.isArray(argString)) {
     return argString.map(e => typeof e !== 'string' ? e + '' : e)
   }
@@ -7,10 +7,10 @@ module.exports = function (argString) {
   argString = argString.trim()
 
   let i = 0
-  let prevC = null
-  let c = null
-  let opening = null
-  const args = []
+  let prevC: string | null = null
+  let c: string | null = null
+  let opening: string | null = null
+  const args: string[] = []
 
   for (let ii = 0; ii < argString.length; ii++) {
     prevC = c
diff --git a/package.json b/package.json
index 2f3a8068..1b44cd1b 100644
--- a/package.json
+++ b/package.json
@@ -4,10 +4,14 @@
   "description": "the mighty option parser used by yargs",
   "main": "index.js",
   "scripts": {
-    "fix": "standard --fix",
-    "test": "c8 --reporter=text --reporter=html  mocha test/*.js",
-    "posttest": "standard",
-    "coverage": "c8 report --check-coverage check-coverage --lines=100 --branches=97 --statements=100"
+    "fix": "standardx --fix && standardx --fix **/*.ts",
+    "pretest": "npm run compile -- -p tsconfig.test.json",
+    "test": "c8 --reporter=text --reporter=html mocha test/*.js",
+    "posttest": "npm run check",
+    "coverage": "c8 report --check-coverage",
+    "check": "standardx && standardx **/*.ts",
+    "compile": "rimraf build && tsc",
+    "prepare": "npm run compile"
   },
   "repository": {
     "type": "git",
@@ -27,20 +31,38 @@
   "author": "Ben Coe <ben@npmjs.com>",
   "license": "ISC",
   "devDependencies": {
+    "@types/chai": "^4.2.11",
+    "@types/mocha": "^7.0.2",
+    "@types/node": "^10.0.3",
+    "@typescript-eslint/eslint-plugin": "^2.25.0",
+    "@typescript-eslint/parser": "^2.25.0",
     "c8": "^7.1.2",
     "chai": "^4.2.0",
+    "eslint": "^7.0.0",
+    "eslint-plugin-import": "^2.20.1",
+    "eslint-plugin-node": "^11.0.0",
+    "gts": "^2.0.0-alpha.4",
     "mocha": "^7.2.0",
-    "standard": "^14.3.4"
+    "rimraf": "^3.0.2",
+    "standardx": "^5.0.0",
+    "typescript": "^3.7.0"
   },
   "dependencies": {
     "camelcase": "^6.0.0",
     "decamelize": "^4.0.0"
   },
   "files": [
-    "lib",
-    "index.js"
+    "index.js",
+    "build",
+    "lib/**/*.js"
   ],
   "engines": {
     "node": ">=10"
+  },
+  "standardx": {
+    "ignore": [
+      "build",
+      "example.js"
+    ]
   }
 }
diff --git a/test/tokenize-arg-string.js b/test/tokenize-arg-string.js
deleted file mode 100644
index 2f35895c..00000000
--- a/test/tokenize-arg-string.js
+++ /dev/null
@@ -1,70 +0,0 @@
-/* global describe, it */
-
-const tokenizeArgString = require('../lib/tokenize-arg-string')
-
-require('chai').should()
-const expect = require('chai').expect
-
-describe('TokenizeArgString', function () {
-  it('handles unquoted string', function () {
-    const args = tokenizeArgString('--foo 99')
-    args[0].should.equal('--foo')
-    args[1].should.equal('99')
-  })
-
-  it('handles unquoted numbers', function () {
-    const args = tokenizeArgString(['--foo', 9])
-    args[0].should.equal('--foo')
-    args[1].should.equal('9')
-  })
-
-  it('handles quoted string with no spaces', function () {
-    const args = tokenizeArgString("--foo 'hello'")
-    args[0].should.equal('--foo')
-    args[1].should.equal("'hello'")
-  })
-
-  it('handles single quoted string with spaces', function () {
-    const args = tokenizeArgString("--foo 'hello world' --bar='foo bar'")
-    args[0].should.equal('--foo')
-    args[1].should.equal("'hello world'")
-    args[2].should.equal("--bar='foo bar'")
-  })
-
-  it('handles double quoted string with spaces', function () {
-    const args = tokenizeArgString('--foo "hello world" --bar="foo bar"')
-    args[0].should.equal('--foo')
-    args[1].should.equal('"hello world"')
-    args[2].should.equal('--bar="foo bar"')
-  })
-
-  it('handles single quoted empty string', function () {
-    const args = tokenizeArgString('--foo \'\' --bar=\'\'')
-    args[0].should.equal('--foo')
-    args[1].should.equal("''")
-    args[2].should.equal("--bar=''")
-  })
-
-  it('handles double quoted empty string', function () {
-    const args = tokenizeArgString('--foo "" --bar=""')
-    args[0].should.equal('--foo')
-    args[1].should.equal('""')
-    args[2].should.equal('--bar=""')
-  })
-
-  it('handles quoted string with embedded quotes', function () {
-    var args = tokenizeArgString('--foo "hello \'world\'" --bar=\'foo "bar"\'')
-    args[0].should.equal('--foo')
-    args[1].should.equal('"hello \'world\'"')
-    args[2].should.equal('--bar=\'foo "bar"\'')
-  })
-
-  // https://github.com/yargs/yargs-parser/pull/100
-  // https://github.com/yargs/yargs-parser/pull/106
-  it('ignores unneeded spaces', function () {
-    const args = tokenizeArgString('  foo  bar  "foo  bar"  ')
-    args[0].should.equal('foo')
-    expect(args[1]).equal('bar')
-    expect(args[2]).equal('"foo  bar"')
-  })
-})
diff --git a/test/tokenize-arg-string.ts b/test/tokenize-arg-string.ts
new file mode 100644
index 00000000..7621d45c
--- /dev/null
+++ b/test/tokenize-arg-string.ts
@@ -0,0 +1,133 @@
+/* global describe, it */
+import { expect, should } from 'chai'
+import { tokenizeArgString } from '../lib/tokenize-arg-string'
+
+should()
+
+describe('TokenizeArgString', function () {
+  it('handles unquoted string', function () {
+    const args = tokenizeArgString('--foo 99')
+    args[0].should.equal('--foo')
+    args[1].should.equal('99')
+  })
+
+  it('handles unquoted numbers', function () {
+    const args = tokenizeArgString(['--foo', 9])
+    args[0].should.equal('--foo')
+    args[1].should.equal('9')
+  })
+
+  it('handles quoted string with no spaces', function () {
+    const args = tokenizeArgString("--foo 'hello'")
+    args[0].should.equal('--foo')
+    args[1].should.equal("'hello'")
+  })
+
+  it('handles single quoted string with spaces', function () {
+    const args = tokenizeArgString("--foo 'hello world' --bar='foo bar'")
+    args[0].should.equal('--foo')
+    args[1].should.equal("'hello world'")
+    args[2].should.equal("--bar='foo bar'")
+  })
+
+  it('handles double quoted string with spaces', function () {
+    const args = tokenizeArgString('--foo "hello world" --bar="foo bar"')
+    args[0].should.equal('--foo')
+    args[1].should.equal('"hello world"')
+    args[2].should.equal('--bar="foo bar"')
+  })
+
+  it('handles single quoted empty string', function () {
+    const args = tokenizeArgString('--foo \'\' --bar=\'\'')
+    args[0].should.equal('--foo')
+    args[1].should.equal("''")
+    args[2].should.equal("--bar=''")
+  })
+
+  it('handles double quoted empty string', function () {
+    const args = tokenizeArgString('--foo "" --bar=""')
+    args[0].should.equal('--foo')
+    args[1].should.equal('""')
+    args[2].should.equal('--bar=""')
+  })
+
+  it('handles quoted string with embedded quotes', function () {
+    var args = tokenizeArgString('--foo "hello \'world\'" --bar=\'foo "bar"\'')
+    args[0].should.equal('--foo')
+    args[1].should.equal('"hello \'world\'"')
+    args[2].should.equal('--bar=\'foo "bar"\'')
+  })
+
+  // https://github.com/yargs/yargs-parser/pull/100
+  // https://github.com/yargs/yargs-parser/pull/106
+  it('ignores unneeded spaces', function () {
+    const args = tokenizeArgString('  foo  bar  "foo  bar"  ')
+    args[0].should.equal('foo')
+    expect(args[1]).equal('bar')
+    expect(args[2]).equal('"foo  bar"')
+  })
+
+  it('handles boolean options', function () {
+    const args = tokenizeArgString('--foo -bar')
+    expect(args[0]).to.equal(('--foo'))
+    expect(args[1]).to.equal(('-bar'))
+  })
+
+  it('handles empty string', function () {
+    const args = tokenizeArgString('')
+    expect(args.length).to.equal(0)
+  })
+
+  it('handles array with unquoted string', function () {
+    const args = tokenizeArgString(['--foo', '99'])
+    args[0].should.equal('--foo')
+    args[1].should.equal('99')
+  })
+
+  it('handles array with quoted string with no spaces', function () {
+    const args = tokenizeArgString(['--foo', "'hello'"])
+    args[0].should.equal('--foo')
+    args[1].should.equal("'hello'")
+  })
+
+  it('handles array with single quoted string with spaces', function () {
+    const args = tokenizeArgString(['--foo', "'hello world'", "--bar='foo bar'"])
+    args[0].should.equal('--foo')
+    args[1].should.equal("'hello world'")
+    args[2].should.equal("--bar='foo bar'")
+  })
+
+  it('handles array with double quoted string with spaces', function () {
+    const args = tokenizeArgString(['--foo', '"hello world"', '--bar="foo bar"'])
+    args[0].should.equal('--foo')
+    args[1].should.equal('"hello world"')
+    args[2].should.equal('--bar="foo bar"')
+  })
+
+  it('handles array with single quoted empty string', function () {
+    const args = tokenizeArgString(['--foo', "''", "--bar=''"])
+    args[0].should.equal('--foo')
+    args[1].should.equal("''")
+    args[2].should.equal("--bar=''")
+  })
+
+  it('handles array with double quoted empty string', function () {
+    const args = tokenizeArgString(['--foo', '""', '--bar=""'])
+    args[0].should.equal('--foo')
+    args[1].should.equal('""')
+    args[2].should.equal('--bar=""')
+  })
+
+  it('handles array with quoted string with embedded quotes', function () {
+    var args = tokenizeArgString(['--foo', '"hello \'world\'"', '--bar=\'foo "bar"\''])
+    args[0].should.equal('--foo')
+    args[1].should.equal('"hello \'world\'"')
+    args[2].should.equal('--bar=\'foo "bar"\'')
+  })
+
+  it('handles array with boolean options', function () {
+    const args = tokenizeArgString(['--foo', '-bar'])
+    expect(args[0]).to.equal('--foo')
+    expect(args[1]).to.equal('-bar')
+  })
+})
diff --git a/tsconfig.json b/tsconfig.json
new file mode 100644
index 00000000..c28e1966
--- /dev/null
+++ b/tsconfig.json
@@ -0,0 +1,11 @@
+{
+  "extends": "./node_modules/gts/tsconfig-google.json",
+  "compilerOptions": {
+    "outDir": "build",
+    "rootDir": ".",
+    "sourceMap": false
+  },
+  "include": [
+    "lib/**/*.ts"
+  ]
+}
diff --git a/tsconfig.test.json b/tsconfig.test.json
new file mode 100644
index 00000000..75a19fe0
--- /dev/null
+++ b/tsconfig.test.json
@@ -0,0 +1,10 @@
+{
+  "extends": "./tsconfig.json",
+  "compilerOptions": {
+    "sourceMap": true
+  },
+  "include": [
+    "lib/**/*.ts",
+    "test/**/*.ts"
+  ]
+}