谁能告诉我这个 javaScript function 是如何工作的？

Question

I am a beginner and recently I have stumbled onto this. I do not understand what this d.getDays() does. Please help me out.

 const dateBuilder = (d) => { let months = ["January", "February", "March", "April", "May", "June", "July", "August", "September", "October", "November", "December"] let days = ["Sunday", "Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday"] let day = days[d.getDay()]; let date = d.getDate(); let month = months[d.getMonth()]; let year = d.getFullYear(); return `${day} ${date} ${month} ${year}` } console.log(dateBuilder(new Date()));

Answer 1

It's a method of the Date object that returns a number representing the day of the week (Monday, Tuesday etc.) that correlates to the days array you have in your code. Read more here . It's basically getting the "name" of the day by using that array days :

let days = ["Sunday", "Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday"]

Answer 2

It seems that d is a Date object.

getDay() is a method being called on that object.