如何忽略数组解构中的某些返回值？

Question

Can I avoid declaring a useless variable when array destructuring when I am only interested in array values beyond index 0?

In the following, I want to avoid declaring a , I am only interested in index 1 and beyond.

 // How can I avoid declaring "a"? const [a, b, ...rest] = [1, 2, 3, 4, 5]; console.log(a, b, rest);

Answer 1

Can I avoid declaring a useless variable when array destructuring when I am only interested in array values beyond index 0?

Yes, if you leave the first index of your assignment empty, nothing will be assigned. This behavior is explained here .

 // The first value in array will not be assigned const [, b, ...rest] = [1, 2, 3, 4, 5]; console.log(b, rest); 

You can use as many commas as you like wherever you like, except after a rest element:

 const [, , three] = [1, 2, 3, 4, 5]; console.log(three); const [, two, , four] = [1, 2, 3, 4, 5]; console.log(two, four); 

The following produces an error:

 const [, ...rest,] = [1, 2, 3, 4, 5]; console.log(rest); 

Answer 2

Ignoring some returned values

You can use ',' ignore return values that you're not interested in:

const [, b, ...rest] = [1, 2, 3, 4, 5];

console.log(b);
console.log(rest);