feat: convert to typescript

BREAKING CHANGE: 

node 8 or higher is now required to use this package. 

commonjs users will now need to import the library as a named export instead. To migrate:

Before:
```
const FilterWarningsPlugin = require('webpack-filter-warnings-plugin');
```

After:
```
const { FilterWarningsPlugin } = require('webpack-filter-warnings-plugin');
```

.babelrc

@@ -1,35 +1,12 @@
 {
   "presets": [
     [
-      "env",
+      "@babel/preset-env",
       {
-        "useBuiltIns": true,
         "targets": {
-          "node": "4.3"
-        },
-        "exclude": [
-          "transform-async-to-generator",
-          "transform-regenerator"
-        ]
+          "node": "8.0"
+        }
       }
     ]
-  ],
-  "plugins": [
-    [
-      "transform-object-rest-spread",
-      {
-        "useBuiltIns": true
-      }
-    ]
-  ],
-  "env": {
-    "test": {
-      "presets": [
-        "env"
-      ],
-      "plugins": [
-        "transform-object-rest-spread"
-      ]
-    }
-  }
-}
+  ]
+}

.gitignore

@@ -1,15 +1,23 @@
+# Tool-generated files
 logs
 *.log
 npm-debug.log*
 .eslintcache
+
+# Directories
 /coverage
 /dist
+/ts-out
 /local
 /reports
 /node_modules
+
+# System meta files
 .DS_Store
 Thumbs.db
+
+# Editors
 .idea
 .vscode
 *.sublime-project
-*.sublime-workspace
+*.sublime-workspace

.npmignore

@@ -0,0 +1,3 @@
+src
+test
+ts-out

README.md

@@ -13,9 +13,10 @@ npm i -D webpack-filter-warnings-plugin
 ```
 
 ## Usage
+
 ```js
 // webpack.config.js
-const FilterWarningsPlugin = require('webpack-filter-warnings-plugin');
+const { FilterWarningsPlugin } = require('webpack-filter-warnings-plugin');
 
 module.exports = {
   // ... rest of webpack config
@@ -27,8 +28,69 @@ module.exports = {
 }
 ```
 
-### Why not use the built in stats.warningsFilter option?
-Currently karma-webpack does not respect the stats.warningsFilter option. Also when excluding all warnings, webpack still says `Compiled with warnings.` when all warnings are filtere. Hopefully this plugin will no longer need to exist one day.
+### Using with Typescript
+
+Webpack Filter Warnings Plugin is completely written in Typescript. As such, it exposes Typescript bindings. 
+
+Before using it, install webpack typings:
+
+```bash
+npm i --save-dev @types/webpack
+```
+
+or
+
+```bash
+yarn add --dev @types/webpack
+```
+
+Use ES imports:
+
+```typescript
+// webpack.config.ts
+import { FilterWarningsPlugin } from 'webpack-filter-warnings-plugin';
+
+```
+
+## Options
+
+Library exposes only one option: `exclude`. It may be one of `RegExp`, `String` or `Function`.
+
+### String as `exclude` filter
+
+When passing string as exclude parameter, phrase is converted to wildcard and matches any phrase that contains it.
+
+```js
+// webpack.config.js
+module.exports = {
+  // ... rest of webpack config
+  plugins: [
+    new FilterWarningsPlugin({ 
+      exclude: 'hide me'
+    })
+  ]
+}
+
+```
+
+This config will match any of `Should hide me`, `Hide me, please`, `HiDe Me` (filter is case insensitive) etc.
+
+### Function as `exclude` filter
+
+```js
+// webpack.config.js
+module.exports = {
+  // ... rest of webpack config
+  plugins: [
+    new FilterWarningsPlugin({ 
+      exclude: (input) => /.*hide.*/.test(input),
+    })
+  ]
+}
+```
+
+## Why not use the built in stats.warningsFilter option?
+Currently karma-webpack does not respect the stats.warningsFilter option. Also when excluding all warnings, webpack still says `Compiled with warnings.` when all warnings are filtered. Hopefully this plugin will no longer need to exist one day.
 
 ## Licence
 MIT

jest.config.js

@@ -0,0 +1,30 @@
+module.exports = {
+  collectCoverageFrom: [
+    'build-tools/**/*.ts',
+    'src/**/*.ts'
+  ],
+  coverageDirectory: 'coverage',
+  coveragePathIgnorePatterns: [
+    '/node_modules/'
+  ],
+  coverageReporters: [
+    'lcov'
+  ],
+  globals: {
+    'ts-jest': {
+      tsConfig: '<rootDir>/test/tsconfig.json',
+    }
+  },
+  moduleDirectories: [
+    'node_modules',
+    'src',
+    'test/unit'
+  ],
+  preset: 'ts-jest',
+  roots: [
+    '<rootDir>/build-tools',
+    '<rootDir>/src',
+    '<rootDir>/test'
+  ],
+  testEnvironment: 'node'
+};