Check out addIndex: Creates a new list iteration function from an existing one by adding two new parameters to its callback function: the current index, and the entire list. This would turn, for instance, Ramda’s simple map function into one that more closely resembles Array.prototype.map. Note that this will only work for functions in which … Read more
You can provide a custom comparison function to JavaScript’s Array#sort method. Use the custom comparison function to ensure the sort order: var sortOrder = [2,3,1,4], items = [{id: 1}, {id: 2}, {id: 3}, {id: 4}]; items.sort(function (a, b) { return sortOrder.indexOf(a.id) – sortOrder.indexOf(b.id); }); MDN: If compareFunction(a, b) returns less than 0, sort a to … Read more
There’s no direct equivalent, but R.filter(R.identity) and R.filter(Boolean) both work. R.reject(R.isNil) is useful for filtering out null/undefined.
Vanilla JS: const fromHexString = (hexString) => Uint8Array.from(hexString.match(/.{1,2}/g).map((byte) => parseInt(byte, 16))); const toHexString = (bytes) => bytes.reduce((str, byte) => str + byte.toString(16).padStart(2, ‘0’), ”); console.log(toHexString(Uint8Array.from([0, 1, 2, 42, 100, 101, 102, 255]))); console.log(fromHexString(‘0001022a646566ff’)); Note: this method trusts its input. If the provided input has a length of 0, an error will be thrown. If the … Read more
Functional Features There is no clear-cut boundary of what defines functional programming or a functional library. Some features of functional languages are built into Javascript: First-class, higher-order functions Lambdas/Anonymous functions, with closures Others are possible to accomplish in Javascript with some care: Immutability Referential Transparency Still others are part of ES6, and partially or fully … Read more