I've seen some uses of ...
but I'm not sure what it's like. Example:
var a = [1, 2, 3];
var b = [4, 5, ...a];
How do you call this operator and how does it work?
I've seen some uses of ...
but I'm not sure what it's like. Example:
var a = [1, 2, 3];
var b = [4, 5, ...a];
How do you call this operator and how does it work?
It transforms an object that is a collection of data into a list of data. Its name is spread ( documentation ).
Can be used to transform an array into input arguments of a function, filling another array , or creating an object based on array .
Do not forget that a string does not stop being an array .
In your example b
will result in 4, 5, 1, 2, 3
.
It's pretty much how he copied that list of elements and stuck elsewhere waiting for a list. This is not how it works because the data collection need not have been created as a literal, but understand so just to better visualize what is occurring.
this would be more or less the same as:
var a = [1, 2, 3];
var b = [4, 5];
b = b.concat(a);
console.log(b);