Answers for "how to change date format in html using javascript"

javascript convert date to yyyy-mm-dd

// `date` is a `Date` object
const formatYmd = date => date.toISOString().slice(0, 10);

// Example
formatYmd(new Date());      // 2020-05-06

change date format in html

<input type="date" name="begin" 
    placeholder="dd-mm-yyyy" value=""
    min="1997-01-01" max="2030-12-31">