javascript - How to add default value and alias using ES6 de-structuring? - Stack Overflow

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I have a specific use case where I want to do a nested de-structuring and assign an alias (rename it to another variable name, say aliasD) as well as a default value to a property. E.g.

const a = { b: { c: [{ d: 'value' }] } };

and while destructuring I only need d but with an alias aliasD and a default value defaultVal. SO I tried below, but I am not sure what I am missing

const a = { b: { c: [{ d: 'value' }] } };
const { b: { c: [first: { d: aliasD = defaultVal }] } } = a;

console.log(aliasD);

I have a specific use case where I want to do a nested de-structuring and assign an alias (rename it to another variable name, say aliasD) as well as a default value to a property. E.g.

const a = { b: { c: [{ d: 'value' }] } };

and while destructuring I only need d but with an alias aliasD and a default value defaultVal. SO I tried below, but I am not sure what I am missing

const a = { b: { c: [{ d: 'value' }] } };
const { b: { c: [first: { d: aliasD = defaultVal }] } } = a;

console.log(aliasD);

But this doesn't work

• javascript
• ecmascript-6
• destructuring

Share Improve this question Follow edited Feb 21, 2017 at 18:00 Aditya Singh asked Feb 21, 2017 at 17:33 Aditya SinghAditya Singh 16.7k1515 gold badges4848 silver badges6969 bronze badges 10

• Can you show what you start with and what you want to end up with? That is not clear to me. – jfriend00 Commented Feb 21, 2017 at 17:39
• Why is there first there? – Andrew Li Commented Feb 21, 2017 at 17:40
• @jfriend00 Doesn't the first line of the question clarify that I want to destructure with an alias and also a default value? Not sure what else you looking for? – Aditya Singh Commented Feb 21, 2017 at 17:42
• @AndrewLi I was trying to alias first item of array. But guess that's not needed. – Aditya Singh Commented Feb 21, 2017 at 17:42
• 1 @AdityaSingh no it's not... – Andrew Li Commented Feb 21, 2017 at 17:44

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1 Answer 1

Sorted by: Reset to default 6

The problem here is for destructuring the array, the correct syntax to get the first value of the array would be:

[varName] = yourArray

Applying that to your example:

const { b: { c: [{ d: aliasD = 'test' }] } } = a;

You can try it out with Babel REPL

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