What is Spread Syntax and Rest Parameters? Are they related to each other?
I read about both but, I couldn't fully understand there use and purpose.
Any help would be much appreciated!
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1stackoverflow.com/questions/20541339/…Bergi– Bergi2017-09-27 19:39:52 +00:00Commented Sep 27, 2017 at 19:39
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stackoverflow.com/questions/37151966/…Bergi– Bergi2017-09-27 19:40:00 +00:00Commented Sep 27, 2017 at 19:40
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To me it makes more sense to close this question as a duplicate of Usage of rest parameter and spread operator in javascript rather than closing it as "too broad" (or whatever the correct term is).Henke– Henke2021-03-14 13:09:51 +00:00Commented Mar 14, 2021 at 13:09
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1 Answer
Spread syntax and Rest Parameters
I strongly recommend taking a look at the documentation, as it is very comprehensive and informative.
Spread Syntax
Spread syntax allows an iterable such as an array expression to be expanded in places where zero or more arguments (for function calls) or elements (for array literals) are expected, or an object expression to be expanded in places where zero or more key-value pairs (for object literals) are expected.
Example:
const array1 = [0, 1, 2, 3];
const array2 = [...array1, 4, 5, 6];
// array2 = [0, 1, 2, 3, 4, 5, 6,]
// Iterates over all properties of the specified object, adding it to the new object
// let objClone = { ...obj };
Rest parameters
The rest parameter syntax allows us to represent an indefinite number of arguments as an array.
Example:
function fun1(...theArgs) {
console.log(theArgs.length);
}
fun1(); // 0
fun1(5); // 1
fun1(5, 6, 7); // 3
