Adding 0 before month index in javascript

Question

I am converting the string month to an index in javascript. But the number needs to have a 2 digit month representation.

This line of code converts the index for me and adds one. This way I have the correct month.

How can I add 0 to the front of the index if the value of the index is only 1 digit? So basically if the month is any of the first 9 months how do I add a 0 in front of the number value of the month?

var expMonth = ["january", "february", "march", "april", "may", "june", "july", "august", "september", "october", "november", "december"].indexOf(req.body.expMonth.toLowerCase()) + 1;

March would output 3. I need March to output 03 But I need October, November, December to output 10, 11, 12. Which they do as of my code now.

Dulpicate http://stackoverflow.com/questions/1267283/how-can-i-create-a-zerofilled-value-using-javascript — Rohan210, Dec 15 '16 at 08:08

Pranav C Balan · Accepted Answer · 2016-12-15T08:12:32.563

1

You can use String#slice method.

console.log(
  ('0' + 1).slice(-2), 
  ('0' + 10).slice(-2), 
  ('0' + 3).slice(-2)
)

With your code :

var expMonth = ('0' + (["january", "february", "march", "april", "may", "june", "july", "august", "september", "october", "november", "december"].indexOf(req.body.expMonth.toLowerCase()) + 1)).slice(-2);

edited Dec 15 '16 at 08:12

answered Dec 15 '16 at 08:07

Pranav C Balan

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See this is what I thought would work. And I keep trying that. but everytime I do this if the output. even with your code you gave me, 21 it appears to be adding the number 1 instead of the index plus one – wuno Dec 15 '16 at 08:11
It is concatenating the value instead of add index + 1 – wuno Dec 15 '16 at 08:12
@wuno : updated – Pranav C Balan Dec 15 '16 at 08:12
Awesome thank you. So basically I just had a syntax error. Would you mind explaining why that was happening to me? I will mark it as answered in 4 minutes. – wuno Dec 15 '16 at 08:14
@wuno : now I just added parathesis for number addition for giving it higher priority... before it simply string concatenation is done – Pranav C Balan Dec 15 '16 at 08:18
Ok thanks man. I was so close. Thanks for actually helping me out bro. have a good night. – wuno Dec 15 '16 at 08:19
@wuno : glad to help you – Pranav C Balan Dec 15 '16 at 08:19

Adding 0 before month index in javascript

1 Answers1