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December 5, 2019 14:17
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How to find duplicates in an array
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| import groupBy from 'lodash.groupby'; | |
| // How to find duplicates, e.g in this example by "label" | |
| // from | |
| // [ | |
| // { label: "brand", key: "1" }, | |
| // { label: "brand", key: "2" }, | |
| // { label: "state", key: "3" } | |
| // { label: "state", key: "4" }, | |
| // { label: "uniq", key: "5" }, | |
| // ] | |
| // to | |
| // [ | |
| // { label: "brand", key: "1" }, | |
| // { label: "brand", key: "2" }, | |
| // { label: "state", key: "3" } | |
| // { label: "state", key: "4" }, | |
| // ] | |
| const items = [ | |
| { label: "brand", key: "1" }, | |
| { label: "brand", key: "2" }, | |
| { label: "state", key: "3" }, | |
| { label: "state", key: "4" }, | |
| { label: "uniq", key: "5" }, | |
| ]; | |
| const itemsByLabel = groupBy(items, 'label'); | |
| const duplicatedItems = Object.values(itemsByLabel) | |
| .filter(group => group.length > 1) | |
| .reduce((acc, group) => [...acc, ...group]) |
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