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Function, that traverse through arrays and objects. The behaviour and callback signature mimics Array.reduce().
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| const isArray = (x: any): x is Array<any> => | |
| Array.isArray(x); | |
| const isObject = (x: any): x is Object => | |
| x !== null && typeof x === 'object' && !(x instanceof Date || x instanceof Number || x instanceof String); | |
| type ReduceRecursiveCb<OUT, IN> = (acc: OUT, x, path: Array<string | number>, source: IN, parent) => OUT; | |
| export const reduceRecursive = <OUT, IN = any>(fn: ReduceRecursiveCb<OUT, IN>) => | |
| (initialValue: OUT, input: any, path: Array<string | number> = [], source: IN = input, parent?: any): OUT => { | |
| let out = input === undefined | |
| ? initialValue | |
| : fn(initialValue, input, path, source, parent); | |
| if (isArray(input)) { | |
| out = input.reduce( | |
| (acc, x, i) => reduceRecursive(fn)(acc, x, [...path, i], source, input), | |
| out | |
| ); | |
| } else if (isObject(input)) { | |
| out = Object.entries(input).reduce( | |
| (acc, [k, x]) => reduceRecursive(fn)(acc, x, [...path, k], source, input), | |
| out | |
| ); | |
| } | |
| return out; | |
| } | |
| // Example: | |
| const users = [ | |
| { | |
| "id": 1, | |
| "name": "Leanne Graham", | |
| "username": "Bret", | |
| "email": "[email protected]", | |
| "address": { | |
| "street": "Kulas Light", | |
| "suite": "Apt. 556", | |
| "city": "Gwenborough", | |
| "zipcode": "92998-3874", | |
| "geo": { | |
| "lat": "-37.3159", | |
| "lng": "81.1496" | |
| } | |
| }, | |
| "phone": "1-770-736-8031 x56442", | |
| "website": "hildegard.org", | |
| "company": { | |
| "name": "Romaguera-Crona", | |
| "catchPhrase": "Multi-layered client-server neural-net", | |
| "bs": "harness real-time e-markets", | |
| "geo": { | |
| "lat": "-37.6102", | |
| "lng": "-80.9653" | |
| } | |
| } | |
| }, | |
| { | |
| "id": 2, | |
| "name": "Ervin Howell", | |
| "username": "Antonette", | |
| "email": "[email protected]", | |
| "address": { | |
| "street": "Victor Plains", | |
| "suite": "Suite 879", | |
| "city": "Wisokyburgh", | |
| "zipcode": "90566-7771", | |
| "geo": { | |
| "lat": "-43.9509", | |
| "lng": "-34.4618" | |
| } | |
| }, | |
| "phone": "010-692-6593 x09125", | |
| "website": "anastasia.net", | |
| "company": { | |
| "name": "Deckow-Crist", | |
| "catchPhrase": "Proactive didactic contingency", | |
| "bs": "synergize scalable supply-chains", | |
| "geo": { | |
| "lat": "-43.6102", | |
| "lng": "-34.0653" | |
| } | |
| } | |
| }, | |
| { | |
| "id": 3, | |
| "name": "Clementine Bauch", | |
| "username": "Samantha", | |
| "email": "[email protected]", | |
| "address": { | |
| "street": "Douglas Extension", | |
| "suite": "Suite 847", | |
| "city": "McKenziehaven", | |
| "zipcode": "59590-4157", | |
| "geo": { | |
| "lat": "-68.6102", | |
| "lng": "-47.0653" | |
| } | |
| }, | |
| "phone": "1-463-123-4447", | |
| "website": "ramiro.info", | |
| "company": { | |
| "name": "Romaguera-Jacobson", | |
| "catchPhrase": "Face to face bifurcated interface", | |
| "bs": "e-enable strategic applications", | |
| "geo": { | |
| "lat": "-68.3102", | |
| "lng": "-47.2653" | |
| } | |
| } | |
| } | |
| ]; | |
| const coords = reduceRecursive<[number, number][]>((acc, x) => { | |
| if (x.geo) | |
| acc.push([x.geo.lat, x.geo.lng]); | |
| return acc; | |
| })([], users); | |
| console.log(coords); | |
| // Output: | |
| // [ | |
| // [ '-37.3159', '81.1496' ], | |
| // [ '-37.6102', '-80.9653' ], | |
| // [ '-43.9509', '-34.4618' ], | |
| // [ '-43.6102', '-34.0653' ], | |
| // [ '-68.6102', '-47.0653' ], | |
| // [ '-68.3102', '-47.2653' ] | |
| // ] |
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