FWIW, while I find needs like this common, too, where Map is sensible instead of Object, it does come out pretty clean:
``` const a = [ {id: "tjc", name: "T.J. Crowder"}, {id: "nc", name: "Naveen Chawla"}, {id: "lh", name: "Lachlan Hunt"} ]; const index = new Map(a.map(member => [ member.name, member ])); ``` Although I’m also puzzled by the suggestion that reducing to an object is an abuse, I do find I wish there were a complement to `Object.entries`: ``` // Object to pairs, and therefore map, is simple: const map = new Map(Object.entries(obj)); // Converting back is also simple ... but not exactly expressive: [ ...map ].reduce((acc, [ key, val ]) => Object.assign(acc, { [key]: val })); ``` Something like `Object.fromEntries` would not provide as much sugar for the OP case as `toObjectByProperty`, but it gets pretty close and has the advantage of being more generic; `toObjectByProperty` strikes me as rather specific for a built-in, especially since one might want to map by a derived value rather than a property. Both map<->object and array<->object cases would become more expressive — plus it follows pretty naturally from the existence of `Object.entries` that there might be a reverse op. ``` Object.fromEntries(a.map(a.map(member => [ member.name, member ]))); ``` In other words, `Object.fromEntries(Object.entries(obj))` would be equivalent in effect to `Object.assign({}, obj)`. Would that adequately address this case you think? My sense is that it’s better to supply generic helpers before more specific helpers when it comes to built-ins.
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