Add TypeScript definition (#125)

Co-authored-by: Sindre Sorhus <[email protected]>

index.d.ts

@@ -0,0 +1,55 @@
+import {WriteStream} from 'node:tty';
+
+export interface Options {
+	/**
+	Whether `process.argv` should be sniffed for `--color` and `--no-color` flags.
+
+	@default true
+	*/
+	readonly sniffFlags?: boolean;
+}
+
+/**
+Levels:
+- `0` - All colors disabled.
+- `1` - Basic 16 colors support.
+- `2` - ANSI 256 colors support.
+- `3` - Truecolor 16 million colors support.
+*/
+export type ColorSupportLevel = 0 | 1 | 2 | 3;
+
+/**
+Detect whether the terminal supports color.
+*/
+export interface ColorSupport {
+	/**
+	The color level.
+	*/
+	level: ColorSupportLevel;
+
+	/**
+	Whether basic 16 colors are supported.
+	*/
+	hasBasic: boolean;
+
+	/**
+	Whether ANSI 256 colors are supported.
+	*/
+	has256: boolean;
+
+	/**
+	Whether Truecolor 16 million colors are supported.
+	*/
+	has16m: boolean;
+}
+
+export type ColorInfo = ColorSupport | false;
+
+export function createSupportsColor(stream: WriteStream, options?: Options): ColorInfo;
+
+declare const supportsColor: {
+	stdout: ColorInfo;
+	stderr: ColorInfo;
+};
+
+export default supportsColor;

index.test-d.ts

@@ -0,0 +1,13 @@
+import {stdout, stderr} from 'node:process';
+import {expectType} from 'tsd';
+import supportsColor, {createSupportsColor, Options, ColorInfo} from './index.js';
+
+const options: Options = {};
+
+expectType<ColorInfo>(supportsColor.stdout);
+expectType<ColorInfo>(supportsColor.stderr);
+
+expectType<ColorInfo>(createSupportsColor(stdout));
+expectType<ColorInfo>(createSupportsColor(stderr));
+
+expectType<ColorInfo>(createSupportsColor(stdout, options));

package.json

@@ -19,11 +19,12 @@
 		"node": ">=12"
 	},
 	"scripts": {
-		"//test": "xo && ava",
-		"test": "xo"
+		"//test": "xo && ava && tsd",
+		"test": "xo && tsd"
 	},
 	"files": [
 		"index.js",
+		"index.d.ts",
 		"browser.js"
 	],
 	"keywords": [
@@ -49,8 +50,10 @@
 		"16m"
 	],
 	"devDependencies": {
+		"@types/node": "^16.11.7",
 		"ava": "^3.15.0",
 		"import-fresh": "^3.3.0",
+		"tsd": "^0.18.0",
 		"typescript": "^4.4.3",
 		"xo": "^0.44.0"
 	}