lodash

How to understand curry and function composition using Lodash flow?

由 ℡╲_俬逩灬. 提交于 2019-11-26 18:17:14
问题 import {flow, curry} from 'lodash'; const add = (a, b) => a + b; const square = n => n * n; const tap = curry((interceptor, n) => { interceptor(n); return n; }); const trace2 = curry((message, n) => { return tap((n) => console.log(`${message} is ${n}`), n); }); const trace = label => { return tap(x => console.log(`== ${ label }: ${ x }`)); }; const addSquare = flow([add, trace('after add'), square]); console.log(addSquare(3, 1)); I started by writing trace2 thinking that trace wouldn't work

Using Lodash to sum values by key

由 孤人 提交于 2019-11-26 18:09:48
问题 How can I sum the values in objects which share a common key? I need to use Lodash for this because I need good performance if these arrays get huge. var prjMgrValues = [ {"proj_mgr":"Jack ProjManager","submitted_dollars":12000}, {"proj_mgr":"Jack ProjManager","submitted_dollars":750000}, {"proj_mgr":"Joe ProjManager","submitted_dollars":45000} ] I'm looking for an output of [ {"proj_mgr":"Jack ProjManager","submitted_dollars":762000}, {"proj_mgr":"Joe ProjManager","submitted_dollars":45000}

How to remove undefined and null values from an object using lodash?

由 依然范特西╮ 提交于 2019-11-26 17:57:34
问题 I have a Javascript object like: var my_object = { a:undefined, b:2, c:4, d:undefined }; How to remove all the undefined properties? False attributes should stay. 回答1: If you want to remove all falsey values then the most compact way is: _.pick(obj, _.identity); For example (Lodash 3.x): _.pick({ a: null, b: 1, c: undefined }, _.identity); >> Object {b: 1} For Lodash 4.x: _.pickBy({ a: null, b: 1, c: undefined }, _.identity); >> Object {b: 1} 回答2: You can simply chain _.omit() with _

How to merge multiple array of object by ID in javascript?

由 心已入冬 提交于 2019-11-26 16:55:42
问题 I want to merge 4 array of object into one array For example: 4 arrays like var arr1 =[ { memberID : "81fs", RatingCW:4.5}, { memberID : "80fs", RatingCW:4}, { memberID : "82fs", RatingCW:5 }, { memberID : "83fs", RatingCW:3}, { memberID : "84fs", RatingCW:4.7} ]; var arr2 =[ { memberID : "80fs", ratingWW: 4}, { memberID : "81fs", ratingWW: 4.5}, { memberID : "83fs", ratingWW: 3}, { memberID : "82fs", ratingWW: 5}, { memberID : "84fs", ratingWW: 3.5} ]; var arr3 = [ { memberID : "80fs",

Error: EACCES: permission denied

由 拜拜、爱过 提交于 2019-11-26 15:46:57
问题 I run npm install lodash but it throws Error: EACCES: permission denied error. I know it is permission issue but as far as I know, sudo permission is not required for installing node module locally. If I run it with sudo, it gets installed inside ~/node_modules folder. drwxrwxr-x is the file permission of existing folder. I can't figure out what might have gone wrong. Below is the error message. npm ERR! tar.unpack untar error /home/rupesh/.npm/lodash/4.13.1/package.tgz npm ERR! Linux 3.13.0

Lodash - difference between .extend() / .assign() and .merge()

由 淺唱寂寞╮ 提交于 2019-11-26 13:57:28
In the Lodash library, can someone provide a better explanation of merge and extend / assign . Its a simple question but the answer evades me nonetheless. Shital Shah Here's how extend / assign works: For each property in source, copy its value as-is to destination. if property values themselves are objects, there is no recursive traversal of their properties. Entire object would be taken from source and set in to destination. Here's how merge works: For each property in source, check if that property is object itself. If it is then go down recursively and try to map child object properties

Merge Array of Objects by Property using Lodash

由 浪子不回头ぞ 提交于 2019-11-26 13:48:32
问题 I have two arrays of objects that represent email addresses that have a label and a value: var original = [ { label: 'private', value: 'private@johndoe.com' }, { label: 'work', value: 'work@johndoe.com' } ]; var update = [ { label: 'private', value: 'me@johndoe.com' }, { label: 'school', value: 'schhol@johndoe.com' } ]; Now I want to compare and merge the two arrays by the label field, so that the result would look like this: var result = [ { label: 'private', value: 'me@johndoe.com' }, {

How can I remove an element from a list, with lodash?

由 ≯℡__Kan透↙ 提交于 2019-11-26 12:07:40
问题 I have an object that looks like this: var obj = { \"objectiveDetailId\": 285, \"objectiveId\": 29, \"number\": 1, \"text\": \"x\", \"subTopics\": [{ \"subTopicId\": 1, \"number\": 1 }, { \"subTopicId\": 2, \"number\": 32 }, { \"subTopicId\": 3, \"number\": 22 }] } var stToDelete = 2; I have lodash installed in my application for other things. Is there an efficient way to use lodash to delete the entry: {\"subTopicId\":2, \"number\":32} from the obj object? Or is there a javascript way to do

How to filter keys of an object with lodash?

由 落花浮王杯 提交于 2019-11-26 12:06:01
问题 I have an object with some keys, and I want to only keep some of the keys with their value? I tried with filter : var data = { \"aaa\":111, \"abb\":222, \"bbb\":333 }; var result = _.filter(data, function(value, key) { return key.startsWith(\"a\"); }) console.log(result); But it prints an array: [111, 222] Which is not what I want. How to do it with lodash? Or something else if lodash is not working? Live demo: http://jsbin.com/moqufevigo/1/edit?js,output 回答1: Lodash has a _.pickBy function

Angular 4 HttpClient Query Parameters

由 半城伤御伤魂 提交于 2019-11-26 11:48:49
问题 I have been looking for a way to pass query parameters into an API call with the new HttpClientModule \'s HttpClient and have yet to find a solution. With the old Http module you would write something like this. getNamespaceLogs(logNamespace) { // Setup log namespace query parameter let params = new URLSearchParams(); params.set(\'logNamespace\', logNamespace); this._Http.get(`${API_URL}/api/v1/data/logs`, { search: params }) } This would result in an API call to the following URL: localhost
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