Answers for "how get part of array with first and last index javascript"

last index array javascript

var colors = ["red","blue","green"];
var green = colors[colors.length - 1]; //get last item in the array

how to get first and last element of array in javascript

The rest parameter can only use at the end not anywhere else in the destructuring so it won't work as you expected.

Instead, you can destructor certain properties(an array is also an object in JS), for example, 0 for first and index of the last element for last.

let array = [1,2,3,4,5,6,7,8,9,0]

let {0 : a ,[array.length - 1] : b} = array;
console.log(a, b)
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Or its better way to extract length as an another variable and get last value based on that ( suggested by @Bergi) , it would work even there is no variable which refers the array.

let {0 : a ,length : l, [l - 1] : b} = [1,2,3,4,5,6,7,8,9,0];
console.log(a, b)