javascript - 我应该避免在reduce中使用对象散布吗？(Should I avoid using object spread in reduce?)

Question

Given the following example:

(给出以下示例：)

// option 1
items.reduce((values, item) => ({
     ...values,
     [item.id]: item.name
}), {})


// option 2
items.reduce((values, item) => {
    values[item.id] = item.name;
    return values;
}, {});

Is there a best practice pro or contra using object spread syntax in this case?

(在这种情况下，是否存在使用对象传播语法的最佳实践专家或反对者？)

  ask by guy mograbi translate from so

Answer 1

In the first code, you're creating a new object for every iteration of .reduce .

(在第一个代码中，您将为.reduce每次迭代创建一个新对象。)

In certain engines, this may be slightly less efficient than your second code, which only creates a single object.

(在某些引擎中，这可能比第二个代码（仅创建一个对象）的效率略低。)

(That said, efficiency rarely matters much; code clarity is much more important in most situations).

(（也就是说，效率几乎没有多大意义；在大多数情况下，代码的清晰性更为重要）。)

But, for this situation, there's an even more suitable method to use when creating an object from an array, which avoids the slightly clunky syntax of reduce :

(但是，对于这种情况，从数组创建对象时，还有一种更合适的方法可以使用，它避免了reduce笨拙语法：)

const output = Object.fromEntries(
  items.map(item => [item.id, item])
);

 const items = [ { id: 5, val: 5 }, { id: 10, val: 10 }, { id: 15, val: 15 }, ]; const output = Object.fromEntries( items.map(item => [item.id, item]) ); console.log(output); 

That said, keep in mind that Object.fromEntries is a relatively new feature, so if this is meant for a public-facing website, make sure to include a polyfill.

(也就是说，请记住Object.fromEntries是一个相对较新的功能，因此，如果这是面向面向公众的网站，请确保包含polyfill。)