Performs left-to-right function composition for asynchronous functions.
Use Array.prototype.reduce() with the spread operator (...) to perform left-to-right function composition using Promise.then(). The functions can return a combination of: simple values, Promise's, or they can be defined as async ones returning through await. All functions must be unary.
const pipeAsyncFunctions = (...fns) => arg => fns.reduce((p, f) => p.then(f), Promise.resolve(arg)); -
const sum = pipeAsyncFunctions( +
+const sum = pipeAsyncFunctions( x => x + 1, x => new Promise(resolve => setTimeout(() => resolve(x + 2), 1000)), x => x + 3, async x => (await x) + 4 ); -(async () => { +(async() => { console.log(await sum(5)); // 15 (after one second) })();
Performs left-to-right function composition.
Use Array.prototype.reduce() with the spread operator (...) to perform left-to-right function composition. The first (leftmost) function can accept one or more arguments; the remaining functions must be unary.
const pipeFunctions = (...fns) => fns.reduce((f, g) => (...args) => g(f(...args))); diff --git a/docs/index.html b/docs/index.html index 77052edad..73e0effb7 100644 --- a/docs/index.html +++ b/docs/index.html @@ -407,12 +407,13 @@
Takes a predicate and array, like Array.prototype.filter(), but only keeps x if pred(x) === false.
const reject = (pred, array) => array.filter((...args) => !pred(...args));
reject(x => x % 2 === 0, [1, 2, 3, 4, 5]); // [1, 3, 5] reject(word => word.length > 4, ['Apple', 'Pear', 'Kiwi', 'Banana']); // ['Pear', 'Kiwi'] -
Removes elements from an array for which the given function returns false.
Use Array.prototype.filter() to find array elements that return truthy values and Array.prototype.reduce() to remove elements using Array.prototype.splice(). The func is invoked with three arguments (value, index, array).
const remove = (arr, func) => +
Removes elements from an array for which the given function returns false.
Use Array.prototype.filter() to find array elements that return truthy values and Array.prototype.reduce() to remove elements using Array.prototype.splice(). The func is invoked with three arguments (value, index, array).
+const remove = (arr, func) => Array.isArray(arr) ? arr.filter(func).reduce((acc, val) => { - arr.splice(arr.indexOf(val), 1); - return acc.concat(val); - }, []) + arr.splice(arr.indexOf(val), 1); + return acc.concat(val); + }, []) : [];
remove([1, 2, 3, 4], n => n % 2 === 0); // [2, 4]
Returns a random element from an array.
Use Math.random() to generate a random number, multiply it by length and round it off to the nearest whole number using Math.floor(). This method also works with strings.
const sample = arr => arr[Math.floor(Math.random() * arr.length)]; diff --git a/docs/math.html b/docs/math.html index ad21ae6e8..f1a9bb838 100644 --- a/docs/math.html +++ b/docs/math.html @@ -152,8 +152,8 @@ own individual rating by supplying it as the third argument.
Calculates the factorial of a number.
Use recursion. If n is less than or equal to 1, return 1. Otherwise, return the product of n and the factorial of n - 1. Throws an exception if n is a negative number.
const factorial = n => n < 0 ? (() => { - throw new TypeError('Negative numbers are not allowed!'); - })() + throw new TypeError('Negative numbers are not allowed!'); + })() : n <= 1 ? 1 : n * factorial(n - 1); diff --git a/docs/node.html b/docs/node.html index 1e6cdd1df..90c095458 100644 --- a/docs/node.html +++ b/docs/node.html @@ -127,7 +127,7 @@ console.log< hasFlags('-s'); // true hasFlags('--test', 'cool=true', '-s'); // true hasFlags('special'); // false -
Creates a hash for a value using the SHA-256 algorithm. Returns a promise.
Use crypto API to create a hash for the given value.
const crypto = require('crypto'); +
Creates a hash for a value using the SHA-256 algorithm. Returns a promise.
Use crypto API to create a hash for the given value, setTimeout to prevent blocking on a long operation, and a Promise to give it a familiar interface.
const crypto = require('crypto'); const hashNode = val => new Promise(resolve => setTimeout( diff --git a/docs/object.html b/docs/object.html index 31acfc9ee..0d1b6aed9 100644 --- a/docs/object.html +++ b/docs/object.html @@ -178,9 +178,9 @@ o[1in obj ? obj[target] : Object.values(obj).reduce((acc, val) => { - if (acc !== undefined) return acc; - if (typeof val === 'object') return dig(val, target); - }, undefined); + if (acc !== undefined) return acc; + if (typeof val === 'object') return dig(val, target); + }, undefined);
const data = { level1: { level2: { diff --git a/snippets/dig.md b/snippets/dig.md index 737130b6e..c97559833 100644 --- a/snippets/dig.md +++ b/snippets/dig.md @@ -10,9 +10,9 @@ const dig = (obj, target) => target in obj ? obj[target] : Object.values(obj).reduce((acc, val) => { - if (acc !== undefined) return acc; - if (typeof val === 'object') return dig(val, target); - }, undefined); + if (acc !== undefined) return acc; + if (typeof val === 'object') return dig(val, target); + }, undefined); ``` ```js diff --git a/snippets/factorial.md b/snippets/factorial.md index cf3acc9cc..86ebe69b6 100644 --- a/snippets/factorial.md +++ b/snippets/factorial.md @@ -11,8 +11,8 @@ Throws an exception if `n` is a negative number. const factorial = n => n < 0 ? (() => { - throw new TypeError('Negative numbers are not allowed!'); - })() + throw new TypeError('Negative numbers are not allowed!'); + })() : n <= 1 ? 1 : n * factorial(n - 1); diff --git a/snippets/pipeAsyncFunctions.md b/snippets/pipeAsyncFunctions.md index 8c93add3b..61b850a39 100644 --- a/snippets/pipeAsyncFunctions.md +++ b/snippets/pipeAsyncFunctions.md @@ -11,13 +11,14 @@ const pipeAsyncFunctions = (...fns) => arg => fns.reduce((p, f) => p.then(f), Pr ``` ```js + const sum = pipeAsyncFunctions( x => x + 1, x => new Promise(resolve => setTimeout(() => resolve(x + 2), 1000)), x => x + 3, async x => (await x) + 4 ); -(async () => { +(async() => { console.log(await sum(5)); // 15 (after one second) })(); ``` diff --git a/snippets/remove.md b/snippets/remove.md index a8c472774..1c457d2d9 100644 --- a/snippets/remove.md +++ b/snippets/remove.md @@ -6,12 +6,13 @@ Use `Array.prototype.filter()` to find array elements that return truthy values The `func` is invoked with three arguments (`value, index, array`). ```js + const remove = (arr, func) => Array.isArray(arr) ? arr.filter(func).reduce((acc, val) => { - arr.splice(arr.indexOf(val), 1); - return acc.concat(val); - }, []) + arr.splice(arr.indexOf(val), 1); + return acc.concat(val); + }, []) : []; ``` diff --git a/test/_30s.js b/test/_30s.js index b5d57f74d..a0309377b 100644 --- a/test/_30s.js +++ b/test/_30s.js @@ -267,9 +267,9 @@ const dig = (obj, target) => target in obj ? obj[target] : Object.values(obj).reduce((acc, val) => { - if (acc !== undefined) return acc; - if (typeof val === 'object') return dig(val, target); - }, undefined); + if (acc !== undefined) return acc; + if (typeof val === 'object') return dig(val, target); + }, undefined); const digitize = n => [...`${n}`].map(i => parseInt(i)); const distance = (x0, y0, x1, y1) => Math.hypot(x1 - x0, y1 - y0); const drop = (arr, n = 1) => arr.slice(n); @@ -341,8 +341,8 @@ const extendHex = shortHex => const factorial = n => n < 0 ? (() => { - throw new TypeError('Negative numbers are not allowed!'); - })() + throw new TypeError('Negative numbers are not allowed!'); + })() : n <= 1 ? 1 : n * factorial(n - 1); @@ -985,12 +985,13 @@ const reducedFilter = (data, keys, fn) => }, {}) ); const reject = (pred, array) => array.filter((...args) => !pred(...args)); + const remove = (arr, func) => Array.isArray(arr) ? arr.filter(func).reduce((acc, val) => { - arr.splice(arr.indexOf(val), 1); - return acc.concat(val); - }, []) + arr.splice(arr.indexOf(val), 1); + return acc.concat(val); + }, []) : []; const removeNonASCII = str => str.replace(/[^\x20-\x7E]/g, ''); const renameKeys = (keysMap, obj) =>