I am having some issues displaying data from my backend API because the incoming dates are formatted incorrectly.

Currently, day and month numbers are entered without a preceding '0' if they are less than 10. For example, 9 should be 09

All incoming dates are in this format: year/month/day.

How can I transform the dates to a format with preceding zeros for numbers less than 10?

My current code:

let date = '2021/1/31';

const addZeros = (date) => {
  const year = date.split('/')[0];
  const month = date.split('/')[1];
  const day = date.split('/')[2];

  return `${year}-${month}-${day}`;
};

console.log(addZeros(date));

<iframe name="sif1" sandbox="allow-forms allow-modals allow-scripts" frameborder="0"></iframe>

Tests:

2021/9/14 --> 2021/09/14

2021/1/7 --> 2021/01/07

2021/10/17 --> 2021/10/17

CodePudding user response：

You can easily achieve the result using split, map, and join.

function convertDate(str) {
  return str
    .split("/")
    .map((s) => {
      const num = parseInt(s);
      return num < 10 ? `0${s}` : s;
    })
    .join("/");
}

console.log(convertDate("2021/9/14")); //--> 2021/09/14
console.log(convertDate("2021/1/7")); //--> 2021/01/07
console.log(convertDate("2021/10/17")); //--> 2021/10/17

<iframe name="sif2" sandbox="allow-forms allow-modals allow-scripts" frameborder="0"></iframe>

CodePudding user response：

const addZeros = (date) => {
  let [year, month, day] = date.split('/');
  month = month.length == 1 ? `0${month}` : month; 
  day = day.length == 1 ? `0${day}` : day; 

  return `${year}-${month}-${day}`;
};


const test = (date, formatDate) => {
  if ( addZeros(date) == formatDate )
    console.log("Success!")
  else
    console.log(`Error: Expected: ${formatDate}, Receive: addZeros(date)`)
}

test('2021/1/31', '2021-01-31')
test('2021/11/1', '2021-11-01')