While
slice()allows us to be selective about what elements of an array to copy, among several other useful tasks, ES6's new spread operator allows us to easily copy all of an array's elements, in order, with a simple and highly readable syntax. The spread syntax simply looks like this:...In practice, we can use the spread operator to copy an array like so:
let thisArray = [true, true, undefined, false, null];
let thatArray = [...thisArray];
thatArrayequals[true, true, undefined, false, null].thisArrayremains unchanged andthatArraycontains the same elements asthisArray.Try it out!
I have defined a function,copyMachinewhich takesarr(an array) andnum(a number) as arguments. The function is supposed to return a new array made up ofnumcopies ofarr. I have done most of the work for you, but it doesn't work quite right yet. Modify the function using spread syntax so that it works correctly.
function copyMachine(arr, num) {
let newArr = [];
while (num >= 1) {
// Only change code below this line
// Only change code above this line
num--;
}
return newArr;
}
console.log(copyMachine([true, false, true], 2));
- Answer:
function copyMachine(arr, num) {
let newArr = [];
while (num >= 1) {
newArr.push([...arr]) <----
num--;
}
return newArr;
}
console.log(copyMachine([true, false, true], 2)); will display
[[true, false, true ], [true, false, true]]
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