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javascriptpropertiesecmascript-6clonedestructuring

In JavaScript ES6, how do I take just a few properties from a hash?

I have an object with some properties. I would like to extract a few well-know properties, skipping over any that are not present.

Something like this: 

let x = {a: 1, b: 2, c: 3};
let y = take a, b, d from x; // Not real JS!

With y now looking like this: 

{a: 1, b: 2} // Note that d is missing!

Is there an operator or method that does this?

Solution

  • Another way to do it is by destructuring:

    let {a, b, d} = x;
let y = {a, b, d};

    This automatically takes out the properties you want to use. Then you can put them back together with an object literal, which in ES6 doesn't require you to do { a: a, b : b }. You can just write { a, b } instead, if the names are the same.

    In this case, a, b and d are also copied.