javascript - Difference between Object.assign and using [...] syntax? -

i have code here , wondering if same thing or different. pretty sure these both suppose same wasnt sure if doing right.

let zonecomment = updatedmap[action.comment.zone]         ? [...updatedmap[action.comment.zone]] : []; 

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let zonecomment = updatedmap[action.comment.zone]           ? object.assign([], updatedmap[action.comment.zone]) : []; 

if these same should use or matter? want use best practice if opinion of better please state so.

in particular case not same.

the reason have array, not object.

doing ... on array spread out elements in array (but not properties)

doing object.assign expects object treat array object , copy enumerable own properties it, not elements:

const = [1, 2, 3]  a.test = 'example'    const 1 = [...a] // [1, 2, 3]  const 2 = object.assign([], a) // { '0': 1, '1': 2, '2': 3, 'test': 'example' }    console.log('\none');  (let prop in one) {    console.log(prop);  }    console.log('\ntwo');  (let prop in two) {    console.log(prop);  }

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however, if compare ... operator applied on object object.assign, same:

// same result  const = { name: 'test' }  console.log({ ...a })  console.log(object.assign({}, a))

except ... creates new object object.assign allows mutate existing object.

// same result  const = { name: 'test' }  const b = { ...a, name: 'change' };    console.log(a.name); // test  object.assign(a, { name: 'change'})  console.log(a.name); // change

keep in mind object.assign part of language whereas object spread still proposal , require preprocessing step (transpilation) tool babel.

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