From 64d28164ef291e30f3c4a9692041392a88770dbd Mon Sep 17 00:00:00 2001 From: Daniel Ramos Date: Wed, 13 Dec 2017 10:27:43 +0000 Subject: [PATCH 1/6] Create promisify.md --- README.md | 19 +++++++++++++++++++ snippets/promisify.md | 17 +++++++++++++++++ 2 files changed, 36 insertions(+) create mode 100644 snippets/promisify.md diff --git a/README.md b/README.md index 7308593a0..557d44232 100644 --- a/README.md +++ b/README.md @@ -42,6 +42,7 @@ * [Object from key value pairs](#object-from-key-value-pairs) * [Pipe](#pipe) * [Powerset](#powerset) +* [Promisify](#promisify) * [Random integer in range](#random-integer-in-range) * [Random number in range](#random-number-in-range) * [Randomize order of array](#randomize-order-of-array) @@ -416,6 +417,24 @@ const powerset = arr => // powerset([1,2]) -> [[], [1], [2], [2,1]] ``` +### Promisify + +Creates a promise version of the given callback-style function. In Node 8+, you +can use [`util.promisify`](https://nodejs.org/api/util.html#util_util_promisify_original) + +```js +const promisify = func => + (...args) => + new Promise((resolve, reject) => + func(...args, (err, result) => + err + ? reject(err) + : resolve(result)) + ) +// const stat = promisify(fs.stat) +// When called, stat returns a promise +``` + ### Random integer in range Use `Math.random()` to generate a random number and map it to the desired range, using `Math.floor()` to make it an integer. diff --git a/snippets/promisify.md b/snippets/promisify.md new file mode 100644 index 000000000..b2007a5ab --- /dev/null +++ b/snippets/promisify.md @@ -0,0 +1,17 @@ +### Promisify + +Creates a promise version of the given callback-style function. In Node 8+, you +can use [`util.promisify`](https://nodejs.org/api/util.html#util_util_promisify_original) + +```js +const promisify = func => + (...args) => + new Promise((resolve, reject) => + func(...args, (err, result) => + err + ? reject(err) + : resolve(result)) + ) +// const stat = promisify(fs.stat) +// When called, stat returns a promise +``` From 3e763d0b2337905c38dfc8d68ed23098e5cd16e3 Mon Sep 17 00:00:00 2001 From: Daniel Ramos Date: Wed, 13 Dec 2017 10:29:34 +0000 Subject: [PATCH 2/6] Fixed typo in promisify.md --- README.md | 2 +- snippets/promisify.md | 2 +- 2 files changed, 2 insertions(+), 2 deletions(-) diff --git a/README.md b/README.md index 557d44232..ea30128d0 100644 --- a/README.md +++ b/README.md @@ -419,7 +419,7 @@ const powerset = arr => ### Promisify -Creates a promise version of the given callback-style function. In Node 8+, you +Creates a promisified version of the given callback-style function. In Node 8+, you can use [`util.promisify`](https://nodejs.org/api/util.html#util_util_promisify_original) ```js diff --git a/snippets/promisify.md b/snippets/promisify.md index b2007a5ab..efecd794a 100644 --- a/snippets/promisify.md +++ b/snippets/promisify.md @@ -1,6 +1,6 @@ ### Promisify -Creates a promise version of the given callback-style function. In Node 8+, you +Creates a promisified version of the given callback-style function. In Node 8+, you can use [`util.promisify`](https://nodejs.org/api/util.html#util_util_promisify_original) ```js From 46e8ff5d24ba3425d0e1e9964e639a387eae713b Mon Sep 17 00:00:00 2001 From: Daniel Ramos Date: Wed, 13 Dec 2017 10:33:39 +0000 Subject: [PATCH 3/6] Improving example in promisify.md --- README.md | 2 +- snippets/promisify.md | 2 +- 2 files changed, 2 insertions(+), 2 deletions(-) diff --git a/README.md b/README.md index ea30128d0..01a7f9c30 100644 --- a/README.md +++ b/README.md @@ -432,7 +432,7 @@ const promisify = func => : resolve(result)) ) // const stat = promisify(fs.stat) -// When called, stat returns a promise +// stat('foo.txt') -> Promise resolves if `foo.txt` exists, otherwise rejects ``` ### Random integer in range diff --git a/snippets/promisify.md b/snippets/promisify.md index efecd794a..b1c34a20c 100644 --- a/snippets/promisify.md +++ b/snippets/promisify.md @@ -13,5 +13,5 @@ const promisify = func => : resolve(result)) ) // const stat = promisify(fs.stat) -// When called, stat returns a promise +// stat('foo.txt') -> Promise resolves if `foo.txt` exists, otherwise rejects ``` From f6c181e0f4e03d523070448dae937455f0a82134 Mon Sep 17 00:00:00 2001 From: Angelos Chalaris Date: Wed, 13 Dec 2017 12:39:24 +0200 Subject: [PATCH 4/6] Update promisify.md --- snippets/promisify.md | 4 +--- 1 file changed, 1 insertion(+), 3 deletions(-) diff --git a/snippets/promisify.md b/snippets/promisify.md index b1c34a20c..d6b437589 100644 --- a/snippets/promisify.md +++ b/snippets/promisify.md @@ -8,9 +8,7 @@ const promisify = func => (...args) => new Promise((resolve, reject) => func(...args, (err, result) => - err - ? reject(err) - : resolve(result)) + err ? reject(err) : resolve(result)); ) // const stat = promisify(fs.stat) // stat('foo.txt') -> Promise resolves if `foo.txt` exists, otherwise rejects From 7490c51ae783097d5e497d20a1528680f1d8b10a Mon Sep 17 00:00:00 2001 From: Daniel Ramos Date: Wed, 13 Dec 2017 12:15:39 +0000 Subject: [PATCH 5/6] Moving semicolon, changing example in promisify.md --- snippets/promisify.md | 11 +++++------ 1 file changed, 5 insertions(+), 6 deletions(-) diff --git a/snippets/promisify.md b/snippets/promisify.md index d6b437589..f9516aeed 100644 --- a/snippets/promisify.md +++ b/snippets/promisify.md @@ -1,15 +1,14 @@ ### Promisify -Creates a promisified version of the given callback-style function. In Node 8+, you -can use [`util.promisify`](https://nodejs.org/api/util.html#util_util_promisify_original) +Use currying to return a function returning a Promise that calls the original function. Use the rest operator to pass in all the parameters. In Node 8+, you can use [`util.promisify`](https://nodejs.org/api/util.html#util_util_promisify_original) ```js const promisify = func => (...args) => new Promise((resolve, reject) => func(...args, (err, result) => - err ? reject(err) : resolve(result)); - ) -// const stat = promisify(fs.stat) -// stat('foo.txt') -> Promise resolves if `foo.txt` exists, otherwise rejects + err ? reject(err) : resolve(result)) + ); +// const delay = promisify((d, cb) => setTimeout(cb, d)) +// delay(2000).then(() => console.log('Hi!')) -> Promise resolves after 2s ``` From 32b9834837f1018ec5b3324af3c921277534c5d6 Mon Sep 17 00:00:00 2001 From: Angelos Chalaris Date: Wed, 13 Dec 2017 14:17:24 +0200 Subject: [PATCH 6/6] Update promisify.md --- snippets/promisify.md | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/snippets/promisify.md b/snippets/promisify.md index f9516aeed..bdedec054 100644 --- a/snippets/promisify.md +++ b/snippets/promisify.md @@ -1,6 +1,9 @@ ### Promisify -Use currying to return a function returning a Promise that calls the original function. Use the rest operator to pass in all the parameters. In Node 8+, you can use [`util.promisify`](https://nodejs.org/api/util.html#util_util_promisify_original) +Use currying to return a function returning a `Promise` that calls the original function. +Use the `...rest` operator to pass in all the parameters. + +*In Node 8+, you can use [`util.promisify`](https://nodejs.org/api/util.html#util_util_promisify_original)* ```js const promisify = func =>