如何使用正则表达式将字符串格式化为mm / dd / yyyy

Question

I have been struggling with this particular regular expression and was wondering if anyone can help. I have an input field that allows users to enter text and if a user enters 01201990 I have a method that converts it to 01/20/19/90 The problem is I don't want the regular expression to continue after the mm/dd/ my end result would look like this 01/20/1990 Any help would be amazing.

    var tmparray = [];
      tmparray.push(
      tmp.model
        // here is where I dont know how to prevent the regex
        // from continuing after 01/20/
        .match(new RegExp('.{1,2}', 'g'))
        .join("/")
    );

    tmp.model = tmparray;
    console.log(tmp.model);

Answer 1

You can use replace() in this case

 document.write('19101992'.replace(/(\\d{2})(\\d{2})(\\d{4})/, '$1/$2/$3')) 

Your code will be like

var tmparray = [];
  tmparray.push(
  tmp.model
    // here is where I dont know how to prevent the regex
    // from continuing after 01/20/
    .replace(/(\d{2})(\d{2})(\d{4})/g, '$1/$2/$3')
);

tmp.model = tmparray;
console.log(tmp.model);

Answer 2

why not just match on: /(\\d{2})(\\d{2})(\\d{4})/

then dd/mm/yyyy is: $1/$2/$3

(I can't see why you'd match {1,2} since you can't tell the difference between 1/11/1990 and 11/1/1990 and in either case would get 11/11/990...)

Answer 3

Try using String.prototype.slice() , String.prototype.concat()

 var str = "01201990" , d = "/" , res = str.slice(0,2).concat(d + str.slice(2,4)).concat(d + str.slice(4)); console.log(res) 

Answer 4

use regex [0-9]{2}(?=(?:[0-9]{4})). for more information please check link https://www.safaribooksonline.com/library/view/regular-expressions-cookbook/9781449327453/ch06s12.html