问题
I was learning how to web scrap in nodejs and came across this kind of array. What is the meaning?
articles = [ //WHAT IS THIS
...articles,
...new_articles
];
回答1:
When we see three dots (…) in the code, it's either rest parameters or the spread operator.
Rest parameters: When three dots (…) is at the end of function parameters it will gather the rest of the list of arguments into an array.
spread operator: Expands elements of an array (or all iterables) into places where multiple elements can fit.
yourFunction(arg1, arg2, ...argN) { // used like rest parameter here
console.log(arg1);
console.log(arg2);
console.log(argN);
}
var inputs = ["a", "b", "c", "d", "e", "f"];
yourFunction(...inputs); // used like spread operator here
Another example of the spread-operator:
const array1 = ['item1', 'item2', 'item3'];
const array2 = ['item5', 'item6', 'item7'];
const items = [...array1, 'item4', ...array2];
console.log(items);
// 'item1', 'item2', 'item3', 'item4', 'item5', 'item6', 'item7'
来源：https://stackoverflow.com/questions/54886728/what-are-those-triple-dot-inside-the-array-marked-it-with-a-comment