Spread operator not working on Objects with string as key

Question

Im writing some code atm with ES6 and Babel (es2015 preset) and I cant spread one Object as I am used to. Normally I would take an Object, use a spread and map the inner content like [...someObject].map(dosomestuff). But my one object does not behave as expected and the only difference I found so far are the keys:

let myObject = {
  'key': content,
  'key2': content,
  'key3': content
};

let array = [...myObject];

Since the object gets generated form a file structure, the keys are formed by variables and can include special chars, so i need to set them like object[key] = value. Why cant I use the spread operator on that object (the array is always empty)? And is there a workaround thats as comfortable as the spread-operator (I dont mean making a new Array with Object.keys and use that)

I want get an array that i can map like [content, content, content].map(doSomething) — knigge
– knigge, Commented May 18, 2017 at 20:53
You can map() keys to values or use Object.values(myObject) — Nenad Vracar
– Nenad Vracar, Commented May 18, 2017 at 20:54
... is not an operator! "Why cant I use the spread operator on that object" You can only use a spread element when that element is iterable. Objects are not iterable. — Felix Kling
– Felix Kling, Commented May 18, 2017 at 21:01

Sagiv b.g · Accepted Answer · 2017-05-18 21:10:50Z

6

The object spread works on bojects, you can't spread an object into an array.

You should spread it to another object:

let myObject = {
  'key': "content1",
  'key2': "content2",
  'key3': "content3"
};

let myObject2 = {
  'key4': 'content4'
}

let newObj= {...myObject, ...myObject2};
console.log(newObj);

This is not part of ES6, but it is on stage 3

edited May 18, 2017 at 21:10

answered May 18, 2017 at 20:55

Sagiv b.g

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3 Comments

Felix Kling Over a year ago

This is invalid ES6.

Sagiv b.g Over a year ago

using babel babeljs.io/docs/plugins/transform-object-rest-spread

Felix Kling Over a year ago

Sure, but how should somebody deduce that from your answer?

Felix Kling · Accepted Answer · 2017-05-18 21:10:36Z

Why cant I use the spread operator on that object?

First of all, ... is not an operator!.

You can only use a spread element when that element is iterable. Objects are not iterable.

And is there a workaround thats as comfortable as the spread-operator (I dont mean making a new Array with Object.keys and use that)

Not in ES6.

I am assuming that you want to get the property values from the object.

If you don't wan to write a helper function and don't necessarily want to use a spread element, you can actually make use of Array.from's ability to take a mapping function as second argument:

Array.from(Array.keys(myObject), x => myObject[x]);

If you really don't want to use Object.keys (Object.values doesn't exist in ES6), then you can write yourself your own helper function as a generator:

function* values(obj) {
  for (var x in obj) {
    // You can use `obj.hasOwnProperty(x)` to guard against inherited properties
    // to achieve the same effect as `Object.keys`
    yield obj[x];
  }
}

let myObject = {
  'key': 'content',
  'key2': 'content1',
  'key3': 'content2'
};

console.log([...values(myObject)]);
// or
console.log(Array.from(values(myObject)));

Eugene · Accepted Answer · 2017-05-18 20:54:13Z

0

With Chrome I see that using spread on an object results in an exception. What does work is using Map

answered May 18, 2017 at 20:54

Eugene

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