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rated 0 times [ 77] [ 3] / answers: 1 / hits: 177412 / 8 Years ago, fri, april 15, 2016, 12:00:00

For some reason I can't find this simple thing in the MDN docs (maybe I'm just missing it).

I expected this to work:

const map = new Map({foo: 'bar'});



map.get('foo'); // 'bar'

...but the first line throws TypeError: (var)[Symbol.iterator] is not a function

How do I make a Map from a plain object? Do I really have to first convert it into an array of arrays of key-value pairs?

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answered 8 Years ago joannam · Accepted Answer

Yes, the Map constructor takes an array of key-value pairs.

Object.entries is a new Object static method available in ES2017 (19.1.2.5).

const map = new Map(Object.entries({foo: 'bar'}));



map.get('foo'); // 'bar'

If you need to support older environments and transpilation is not an option for you, use a polyfill, such as the one recommended by georg:

Object.entries = typeof Object.entries === 'function' ? Object.entries : obj => Object.keys(obj).map(k => [k, obj[k]]);