Add .isBlob() (#162)

Co-authored-by: Sindre Sorhus <sindresorhus@gmail.com>

readme.md

@@ -110,6 +110,7 @@ is.array(value, is.number); // Validate `value` is an array and all of its items
 **Note:** TypeScript users must use `.function_()` because of a TypeScript naming limitation.
 
 ##### .buffer(value)
+##### .blob(value)
 ##### .object(value)
 
 Keep in mind that [functions are objects too](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Functions).

source/index.ts

@@ -34,6 +34,7 @@ const objectTypeNames = [
 	'Observable',
 	'Array',
 	'Buffer',
+	'Blob',
 	'Object',
 	'RegExp',
 	'Date',
@@ -178,6 +179,7 @@ is.array = <T = unknown>(value: unknown, assertion?: (value: T) => value is T):
 };
 
 is.buffer = (value: unknown): value is Buffer => (value as any)?.constructor?.isBuffer?.(value) ?? false;
+is.blob = (value: unknown): value is Blob => isObjectOfType<Blob>('Blob')(value);
 
 is.nullOrUndefined = (value: unknown): value is null | undefined => is.null_(value) || is.undefined(value);
 is.object = (value: unknown): value is object => !is.null_(value) && (typeof value === 'object' || is.function_(value));
@@ -470,6 +472,7 @@ interface Assert {
 	numericString: (value: unknown) => asserts value is string;
 	array: <T = unknown>(value: unknown, assertion?: (element: unknown) => asserts element is T) => asserts value is T[];
 	buffer: (value: unknown) => asserts value is Buffer;
+	blob: (value: unknown) => asserts value is Blob;
 	nullOrUndefined: (value: unknown) => asserts value is null | undefined;
 	object: <Key extends keyof any = string, Value = unknown>(value: unknown) => asserts value is Record<Key, Value>;
 	iterable: <T = unknown>(value: unknown) => asserts value is Iterable<T>;
@@ -572,6 +575,7 @@ export const assert: Assert = {
 		}
 	},
 	buffer: (value: unknown): asserts value is Buffer => assertType(is.buffer(value), 'Buffer', value),
+	blob: (value: unknown): asserts value is Blob => assertType(is.blob(value), 'Blob', value),
 	nullOrUndefined: (value: unknown): asserts value is null | undefined => assertType(is.nullOrUndefined(value), AssertionTypeDescription.nullOrUndefined, value),
 	object: (value: unknown): asserts value is object => assertType(is.object(value), 'Object', value),
 	iterable: <T = unknown>(value: unknown): asserts value is Iterable<T> => assertType(is.iterable(value), AssertionTypeDescription.iterable, value),

test/test.ts

@@ -170,6 +170,14 @@ const types = new Map<string, Test>([
 		],
 		typename: 'Buffer'
 	}],
+	['blob', {
+		is: is.blob,
+		assert: assert.blob,
+		fixtures: [
+			new window.Blob()
+		],
+		typename: 'Blob'
+	}],
 	['object', {
 		is: is.object,
 		assert: assert.object,
@@ -683,6 +691,10 @@ test('is.buffer', t => {
 	testType(t, 'buffer');
 });
 
+test('is.blob', t => {
+	testType(t, 'blob');
+});
+
 test('is.object', t => {
 	const testData = types.get('object');