lodash find duplicates in array code example

Example 1: how to collect keys using lodash javascript

import * as _ from 'lodash';

const objectMap = {'key1': 'value1', 'key2': 'value2'};
const allKeys = _.keys(objectMap); //Returns a string[]. Here it will be ['key1','key2'];

Example 2: lodash find duplicate element index

const _ = require('lodash');
let arr = ["a", "a", "b", "c", "c", "a"];

let result = _.omitBy(
  _.reduce(arr, (a, v, i) => _.set(a, v, (a[v] || []).concat([i])), {} ),
  v => v.length <= 1
);

console.log(result);

Example 3: lodash map

const _quote_filter = _.map(quote_state, (val, key) => {   if (val) {      return key   }})console.log(_quote_filter) //=> [ 'btc', undefined, undefined ]