how to filter arrays and objects.md

https://stackoverflow.com/questions/5072136/javascript-filter-for-objects/37616104

Taken from the above article:

I provide here several solutions:

1.) Using reduce and Object.keys

2.) As (1), in combination with Object.assign

3.) Using map and spread syntax instead of reduce

4.) Using Object.entries and Object.fromEntries

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1.) Example

Object.filter = (obj, predicate) => Object.keys(obj) .filter( key => predicate(obj[key]) ) .reduce( (res, key) => (res[key] = obj[key], res), {} );

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2.) Example

Object.filter = (obj, predicate) => Object.keys(obj) .filter( key => predicate(obj[key]) ) .reduce( (res, key) => Object.assign(res, { [key]: obj[key] }), {} );

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3.) Example

Object.filter = (obj, predicate) => Object.assign(...Object.keys(obj) .filter( key => predicate(obj[key]) ) .map( key => ({ [key]: obj[key] }) ) );

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4.) Example

Object.filter = (obj, predicate) => Object.fromEntries(Object.entries(obj).filter(predicate));

Another Example for use case number 4:

function toArray(obj) { return Object.entries(obj); }

Expected output using toArray function above

toArray({ a: 1, b: 2 }) ➞ [["a", 1], ["b", 2]]

toArray({ shrimp: 15, tots: 12 }) ➞ [["shrimp", 15], ["tots", 12]]

toArray({}) ➞ []

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OTHER RESOURCES

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