Merge pull request #765 from 30-seconds/is-stream

Add isStream

snippets/isDuplexStream.md

@@ -0,0 +1,23 @@
+### isDuplexStream
+
+Checks if the given argument is a duplex (readable and writable) stream.
+
+Check if the value is different from `null`, use `typeof` to check if a value is of type `object` and the `pipe` property is of type `function`.
+Additionally check if the `typeof` the `_read`, `_write` and `_readableState`, `_writableState` properties are `function` and `object` respectively.
+
+```js
+const isDuplexStream = val =>
+  val !== null &&
+  typeof val === 'object' &&
+  typeof val.pipe === 'function' &&
+  typeof val.pipe === 'function' &&
+  typeof val._read === 'function' &&
+  typeof val._readableState === 'object' &&
+  typeof val._write === 'function' &&
+  typeof val._writableState === 'object';
+```
+
+```js
+const Stream = require('stream');
+isDuplexStream(new Stream.Duplex()); // true
+```

snippets/isReadableStream.md

@@ -0,0 +1,20 @@
+### isReadableStream
+
+Checks if the given argument is a readable stream.
+
+Check if the value is different from `null`, use `typeof` to check if the value is of type `object` and the `pipe` property is of type `function`.
+Additionally check if the `typeof` the `_read` and `_readableState` properties are `function` and `object` respectively.
+
+```js
+const isReadableStream = val =>
+  val !== null &&
+  typeof val === 'object' &&
+  typeof val.pipe === 'function' &&
+  typeof val._read === 'function' &&
+  typeof val._readableState === 'object';
+```
+
+```js
+const fs = require('fs');
+isReadableStream(fs.createReadStream('test.txt')); // true
+```

snippets/isStream.md

@@ -0,0 +1,14 @@
+### isStream
+
+Checks if the given argument is a stream.
+
+Check if the value is different from `null`, use `typeof` to check if the value is of type `object` and the `pipe` property is of type `function`.
+
+```js
+const isStream = val => val !== null && typeof val === 'object' && typeof val.pipe === 'function';
+```
+
+```js
+const fs = require('fs');
+isStream(fs.createReadStream('test.txt')); // true
+```

snippets/isWritableStream.md

@@ -0,0 +1,20 @@
+### isWritableStream
+
+Checks if the given argument is a writable stream.
+
+Check if the value is different from `null`, use `typeof` to check if the value is of type `object` and the `pipe` property is of type `function`.
+Additionally check if the `typeof` the `_write` and `_writableState` properties are `function` and `object` respectively.
+
+```js
+const isWritableStream = val =>
+  val !== null &&
+  typeof val === 'object' &&
+  typeof val.pipe === 'function' &&
+  typeof val._write === 'function' &&
+  typeof val._writableState === 'object';
+```
+
+```js
+const fs = require('fs');
+isWritableStream(fs.createWriteStream('test.txt')); // true
+```

tag_database

@@ -139,6 +139,7 @@ isBoolean:type,beginner
 isBrowser:utility,browser,intermediate
 isBrowserTabFocused:browser,beginner
 isDivisible:math,beginner
+isDuplexStream:node,type,intermediate
 isEmpty:type,array,object,string,beginner
 isEven:math,beginner
 isFunction:type,function,beginner
@@ -152,14 +153,17 @@ isPlainObject:type,object,intermediate
 isPrime:math,beginner,intermediate
 isPrimitive:type,function,array,string,intermediate
 isPromiseLike:type,function,promise,intermediate
+isReadableStream:node,type,intermediate
 isSameDate:date,utility,beginner
 isSorted:array,intermediate
+isStream:node,type,intermediate
 isString:type,string,beginner
 isSymbol:type,beginner
 isTravisCI:node,intermediate
 isUndefined:type,beginner
 isUpperCase:string,utility,beginner
 isValidJSON:type,json,intermediate
+isWritableStream:node,type,intermediate
 join:array,intermediate
 JSONtoCSV:array,string,object,advanced
 JSONToFile:node,json,intermediate

test/isDuplexStream/isDuplexStream.js

@@ -0,0 +1,10 @@
+const isDuplexStream = val =>
+  val !== null &&
+  typeof val === 'object' &&
+  typeof val.pipe === 'function' &&
+  typeof val.pipe === 'function' &&
+  typeof val._read === 'function' &&
+  typeof val._readableState === 'object' &&
+  typeof val._write === 'function' &&
+  typeof val._writableState === 'object';
+module.exports = isDuplexStream;

test/isDuplexStream/isDuplexStream.test.js

@@ -0,0 +1,20 @@
+const expect = require('expect');
+const isDuplexStream = require('./isDuplexStream.js');
+const fs = require('fs');
+const Stream = require('stream');
+
+test('isDuplexStream is a Function', () => {
+  expect(isDuplexStream).toBeInstanceOf(Function);
+});
+test('isDuplexStream returns true for read streams', () => {
+  expect(isDuplexStream(fs.createReadStream('isDuplexStream.js'))).toBeTruthy();
+});
+test('isDuplexStream returns true for write streams', () => {
+  expect(isDuplexStream(fs.createWriteStream('isDuplexStream.js'))).toBeTruthy();
+});
+test('isDuplexStream returns true for duplex streams', () => {
+  expect(isDuplexStream(new Stream.Duplex())).toBeTruthy();
+});
+test('isDuplexStream returns false for non-streams', () => {
+  expect(isDuplexStream({})).toBeFalsy();
+});

test/isReadableStream/isReadableStream.js

@@ -0,0 +1,7 @@
+const isReadableStream = val =>
+  val !== null &&
+  typeof val === 'object' &&
+  typeof val.pipe === 'function' &&
+  typeof val._read === 'function' &&
+  typeof val._readableState === 'object';
+module.exports = isReadableStream;

test/isReadableStream/isReadableStream.test.js

@@ -0,0 +1,20 @@
+const expect = require('expect');
+const isReadableStream = require('./isReadableStream.js');
+const fs = require('fs');
+const Stream = require('stream');
+
+test('isReadableStream is a Function', () => {
+  expect(isReadableStream).toBeInstanceOf(Function);
+});
+test('isReadableStream returns true for read streams', () => {
+  expect(isReadableStream(fs.createReadStream('isReadableStream.js'))).toBeTruthy();
+});
+test('isReadableStream returns false for write streams', () => {
+  expect(isReadableStream(fs.createWriteStream('isReadableStream.js'))).toBeFalsy();
+});
+test('isReadableStream returns true for duplex streams', () => {
+  expect(isReadableStream(new Stream.Duplex())).toBeTruthy();
+});
+test('isReadableStream returns false for non-streams', () => {
+  expect(isReadableStream({})).toBeFalsy();
+});

test/isStream/isStream.js

@@ -0,0 +1,2 @@
+const isStream = val => val !== null && typeof val === 'object' && typeof val.pipe === 'function';
+module.exports = isStream;

test/isStream/isStream.test.js

@@ -0,0 +1,20 @@
+const expect = require('expect');
+const isStream = require('./isStream.js');
+const fs = require('fs');
+const Stream = require('stream');
+
+test('isStream is a Function', () => {
+  expect(isStream).toBeInstanceOf(Function);
+});
+test('isStream returns true for read streams', () => {
+  expect(isStream(fs.createReadStream('isStream.js'))).toBeTruthy();
+});
+test('isStream returns true for write streams', () => {
+  expect(isStream(fs.createWriteStream('isStream.js'))).toBeTruthy();
+});
+test('isStream returns true for duplex streams', () => {
+  expect(isStream(new Stream.Duplex())).toBeTruthy();
+});
+test('isStream returns false for non-streams', () => {
+  expect(isStream({})).toBeFalsy();
+});

test/isWritableStream/isWritableStream.js

@@ -0,0 +1,7 @@
+const isWritableStream = val =>
+  val !== null &&
+  typeof val === 'object' &&
+  typeof val.pipe === 'function' &&
+  typeof val._write === 'function' &&
+  typeof val._writableState === 'object';
+module.exports = isWritableStream;

test/isWritableStream/isWritableStream.test.js

@@ -0,0 +1,20 @@
+const expect = require('expect');
+const isWritableStream = require('./isWritableStream.js');
+const fs = require('fs');
+const Stream = require('stream');
+
+test('isWritableStream is a Function', () => {
+  expect(isWritableStream).toBeInstanceOf(Function);
+});
+test('isWritableStream returns false for read streams', () => {
+  expect(isWritableStream(fs.createReadStream('isWritableStream.js'))).toBeFalsy();
+});
+test('isWritableStream returns true for write streams', () => {
+  expect(isWritableStream(fs.createWriteStream('isWritableStream.js'))).toBeTruthy();
+});
+test('isWritableStream returns true for duplex streams', () => {
+  expect(isWritableStream(new Stream.Duplex())).toBeTruthy();
+});
+test('isWritableStream returns false for non-streams', () => {
+  expect(isWritableStream({})).toBeFalsy();
+});