CODEWITHSUNDEEP
ecmascript-6ecmascript-harmony
Matt K
Matt K

Reputation: 4948

ES2015 Destructure object twice in same scope

Is there a clean way to destructure the same variables from 2 similar objects in the same scope?

function(oldState, newState) {
  let {foo, bar} = oldState;
  // do stuff //
  let {foo, bar} = newState; // illegal double declaration in same scope
  {foo, bar} = newState; // illegal, not sure why
  let {foo: foo1, bar: bar1} = newState; // legal but ugly
  foo = newState.foo; // legal, but requires multiple lines
}

Upvotes: 11

Views: 2164

Answers (1)

dfreeman
dfreeman

Reputation: 2834

You can wrap the assignment in parens to reassign the variables via destructuring. The reason this is necessary is because otherwise the { is assumed by the parser to begin a block rather than an object literal or assignment pattern. This blog post explains the situation in more detail.

function(oldState, newState) {
  let {foo, bar} = oldState;
  // do stuff //
  ({foo, bar} = newState);
}

Upvotes: 17

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