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ForEach, Filter and Map implemented using Reduce [typesafe]
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| const testArray = [1, 2, 3]; | |
| // ---- | |
| // MAP | |
| // ---- | |
| const customMap = <T extends unknown>(arr: T[], callback: (value: T) => T) => { | |
| return arr.reduce((mapped: T[], current) => { | |
| mapped.push(callback(current)) | |
| return mapped | |
| }, []) | |
| } | |
| // test | |
| console.log(customMap(testArray, (val) => val * 2)); | |
| // ---- | |
| // FILTER | |
| // ---- | |
| const customFilter = <T extends unknown>(arr: T[], callback: (value: T) => boolean) => { | |
| return arr.reduce((filtered: T[], current) => { | |
| if (callback(current)) { | |
| filtered.push(current); | |
| } | |
| return filtered; | |
| }, []) | |
| } | |
| // test | |
| console.log(customFilter(testArray, (val) => val === 2)); | |
| // ---- | |
| // FOREACH | |
| // ---- | |
| const customForEach = <T extends unknown>(arr: T[], callback: (value: T) => void) => { | |
| return arr.reduce((_, current) => { | |
| callback(current); | |
| return _; | |
| }, null) | |
| } | |
| // test | |
| customForEach(testArray, (val) => console.log("This is: " + val)); | |
| // ---- | |
| You can test the outputs here: https://www.typescriptlang.org/play?ssl=38&ssc=1&pln=1&pc=1#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 |
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