# understory > Composable utility functions based on lodash fp. Latest version **2.0.3** (published 2023-07-18) · ISC license · 0 weekly downloads ## Install ```sh npm install understory pnpm add understory yarn add understory bun add understory ``` ## Health **Score 20/100 (F)** — status: abandoned. Positive: esm support; no vulnerabilities. Warnings: low downloads; no types. Negative: abandoned; low maintenance score. ## Facts | | | |---|---| | Version | 2.0.3 | | Published | 2023-07-18 | | First published | 2014-07-21 | | Weekly downloads | 0 | | License | ISC | | TypeScript types | none | | Module format | ESM | | Node | ^14.13.1 \|\| >=16.0.0 | | Dependencies | 1 | | Unpacked size | 28.2 KB | | Known vulnerabilities | 0 | | Install scripts | no | | GitHub stars | 1 | | Author | Kai Curry | | Maintainers | kaicurry | | Keywords | lodash, fp, data, utility, promise, serial, flow, composable, branch | ## Links - npm: https://www.npmjs.com/package/understory - Repository: https://github.com/cape-io/understory - Issues: https://github.com/cape-io/understory/issues - npm.io page: https://npm.io/package/understory ## Dependencies (1) - [lodash](https://npm.io/package/lodash.md) ^4.17.21 ## Alternatives - [lodash.assign](https://npm.io/package/lodash.assign.md) — 2.3M weekly downloads - [lodash.chunk](https://npm.io/package/lodash.chunk.md) — 1.8M weekly downloads - [react-native-ios-utilities](https://npm.io/package/react-native-ios-utilities.md) — 138.5K weekly downloads - [@technically/lodash](https://npm.io/package/@technically/lodash.md) — 50.9K weekly downloads - [@fluid-topics/ft-icon](https://npm.io/package/@fluid-topics/ft-icon.md) — 20.6K weekly downloads ## Recent versions - 2.0.3 (latest) — 2023-07-18 - 2.0.2 — 2021-09-03 - 2.0.1 — 2021-09-03 - 1.13.1 — 2021-03-08 - 1.13.0 — 2020-10-11 - 1.12.0 — 2020-07-21 - 1.11.0 — 2019-11-22 - 1.10.1 — 2019-11-18 - 1.10.0 — 2019-10-27 - 1.9.0 — 2019-10-17 - 1.8.0 — 2019-10-17 - 1.7.2 — 2019-07-23 - 1.7.1 — 2019-07-11 - 1.7.0 — 2019-03-02 - 1.6.0 — 2019-03-01 - … 22 more at https://npm.io/package/understory/versions ## README # Understory **Version 2 is ESM.** Importing all of lodash/fp.js [#4296](https://github.com/lodash/lodash/issues/4296) Composable utility functions based on or inspired by [lodash](https://lodash.com/docs). For best results learn about `_.flow()` and read the [Lodash FP Guide](https://github.com/lodash/lodash/wiki/FP-Guide). Install [ESLint rules for lodash/fp](https://github.com/jfmengels/eslint-plugin-lodash-fp) by extending eslint with `plugin:lodash-fp/recommended` and including the `lodash-fp` plugin. There are also promise enabled varients of `_.flow` as `flowP` and `_.forEach` as `forEachP`. We call it "understory" because it's close to "underscore" and the understory is the layer of vegetation below the forest canopy. ## branch Curried function form of a conditional ternary expression ### Parameters * `trueVal` **any** The value returned when true. * `falseVal` **any** The value returned when false. * `bool` **any** The value to check truthiness against. Returns **any** The trueVal or falseVal depending on bool. ## overBranch Passes argument to boolCheck function. If true sends same argument to `getTrue` function. ### Parameters * `boolCheck` **([Function][49] | any)** Function that check if value is true. * `getTrue` **([Function][49] | any)** Get the value when true. * `getFalse` **([Function][49] | any)** Optional. Get value when false. (optional, default `identity`) ### Examples ```javascript overBranch(boolCheck, getTrue) ``` Returns **any** Function that accepts a value and returns result of getTrue or getFalse. ## onTrue Passes argument to boolCheck function. If true sends same argument to `getTrue` function. Similar to overBranch but no getFalse option. ### Parameters * `boolCheck` **([Function][49] | any)** Function that check if value is true. * `getValue` **([Function][49] | any)** Get the value when true. * `item` **([Function][49] | any)** The value sent to boolCheck. ### Examples ```javascript onTrue(_.isString, _.toUpper)('foo') // => 'FOO' ``` ```javascript onTrue(_.isString, _.toUpper)(45) // => 45 ``` Returns **any** Result of getValue when true or the untouched item. ## callWith \[callWith description] ### Parameters * `args` **\[type]** \[description] Returns **\[type]** \[description] ## condId * **See**: onTrue if you have one condition. Accepts many \[boolCheck, onTrue] arguments. See \_.cond() for more info. The function or exact match to check item against. If onTrue is a function it is sent the the value like \_.cond() If onTrue is not a function the value of onTrue is returned. ### Parameters * `conditions` **[array][50]** one or more condition arrays \[boolCheck, thenFunc] Returns **any** Result of found thenFunc or if no conditions found return original. ## isFalse Returns true if sent a value that is exactly `false`. ### Parameters * `value` **any** Send it anything ### Examples ```javascript isFalse(1) // => false ``` ```javascript isFalse(false) // => true ``` Returns **bool** Tells you if it is exactly false. ## isZero Returns true if sent a value that is exactly 0. ### Parameters * `value` **any** Send it anything ### Examples ```javascript isZero(0.1) // => false ``` ```javascript isZero(0) // => true ``` Returns **bool** Tells you if it is exactly zero. ## isTrue Returns true if sent a value that is exactly `false`. ### Parameters * `value` **any** Send it anything ### Examples ```javascript isTrue(1) // => false ``` ```javascript isTrue(true) // => true ``` Returns **bool** Tells you if it is exactly false. ## isWorthless \[isWorthless description] ### Parameters * `value` **any** ### Examples ```javascript isWorthless({}) // => true ``` ```javascript isWorthless([' ', null]) // => true ``` ```javascript isWorthless(' ') // => true ``` ```javascript isWorthless({ foo: null, bar: 0 }) // => true ``` Returns **bool** Tells you if value is empty. ## isValue If value is truthy, null, zero, or false. ### Parameters * `value` **any** Returns **bool** Tells you if arg is a value probably worth keeping. ## hasSize Opposite of `_.isEmpty`. Type: [Function][49] ## oneOf A curried version of \_.includes without a rearg. Type: [Function][49] ### Examples ```javascript oneOf([2,3,4])(3) // => true ``` ## isGt Checks to see if second arg is greater than first. See \_.lt Type: [Function][49] ### Examples ```javascript isGt(1)(2) // => true ``` ## isLt Checks to see if second arg is less than first. See \_.gt Type: [Function][49] ### Examples ```javascript isLt(2)(1) // => true ``` ## subtrahend Subtract two numbers. ### Parameters * `subtrahend` **[number][51]** A quantity/number to be subtracted from another. * `minuend` **[number][51]** A quantity/number from which another is to be subtracted. ### Examples ```javascript _.subtrahend(6)(8); // => 2 _.subtrahend(6, 8); // => 2 ``` Returns **[number][51]** Returns the difference. ## addend Add two numbers or strings. ### Parameters * `addend` **([number][51] | [string][52])** A quantity/number to be added to the end of another. * `augend` **([number][51] | [string][52])** A quantity/number from to another is added. ### Examples ```javascript _.addend('c')('ab'); // => 'abc' ``` Returns **[number][51]** Returns the sum. ## roundTo Round number with precision. ### Parameters * `precision` **[number][51]** The precision to round to. * `number` **[number][51]** The number to round. ### Examples ```javascript round(1)(14.23); // => 14.2 ``` Returns **[number][51]** Returns the rounded number. ## arrayToIndex Create an index with keys of arr and all values of val. ### Parameters * `arr` **[array][50]** \[description] * `val` **[Boolean][53]** \[description] (optional, default `true`) Returns **[Object][54]** \[description] ## forEachP Like \_.forEach but can handle a promise generator as the iteratee. Iterates over elements of collection and invokes iteratee for each element. The iteratee is invoked with one argument: (value). Iteratee functions may NOT exit iteration early. ### Parameters * `iteratee` **[Function][49]** The function that should process each item. * `collection` **[Array][50]** The iterable. Each val send to func after previous resolves. Returns **[Promise][55]** The value return value of the last promise. ## mapP map for Promises. Invokes iteratee in serial sequence instead of all at once. ### Parameters * `iteratee` **[Function][49]** The function that should process each item. * `collection` **[Array][50]** The iterable. Each val send to func after previous resolves. Returns **[Promise][55]** The value return value of the last promise. [1]: #branch [2]: #parameters [3]: #overbranch [4]: #parameters-1 [5]: #examples [6]: #ontrue [7]: #parameters-2 [8]: #examples-1 [9]: #callwith [10]: #parameters-3 [11]: #condid [12]: #parameters-4 [13]: #isfalse [14]: #parameters-5 [15]: #examples-2 [16]: #iszero [17]: #parameters-6 [18]: #examples-3 [19]: #istrue [20]: #parameters-7 [21]: #examples-4 [22]: #isworthless [23]: #parameters-8 [24]: #examples-5 [25]: #isvalue [26]: #parameters-9 [27]: #hassize [28]: #oneof [29]: #examples-6 [30]: #isgt [31]: #examples-7 [32]: #islt [33]: #examples-8 [34]: #subtrahend [35]: #parameters-10 [36]: #examples-9 [37]: #addend [38]: #parameters-11 [39]: #examples-10 [40]: #roundto [41]: #parameters-12 [42]: #examples-11 [43]: #arraytoindex [44]: #parameters-13 [45]: #foreachp [46]: #parameters-14 [47]: #mapp [48]: #parameters-15 [49]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Statements/function [50]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Array [51]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Number [52]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/String [53]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Boolean [54]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Object [55]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Promise --- _Source: https://npm.io/package/understory · Machine-readable twin of the npm.io package page. 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