Question

I need to extract the date from json :

/Date(1224043200000)/ 

I saw That I can do it by :

var date = new Date(parseInt('/Date(1224043200000)/'.substr(6))); 
                                    ^
                                    |
------------------------------0123456

But how does substr knows to ignore the last chars ?
[)/]

I’ve searched at mdn , but couldn’t find the documented behaviour.

Answer 1

.substr() return everything after the 6th char.

But parseInt() will parse all numeric chars until it reaches a non numeric char, so the ignoring happens by parseInt

---

Quoting the docs

If parseInt encounters a character that is not a numeral in the specified radix, it ignores it and all succeeding characters and returns the integer value parsed up to that point. parseInt truncates numbers to integer values. Leading and trailing spaces are allowed.