function parse(str) {
if(!/^(\d){8}$/.test(str)) return "invalid date";
var y = str.substr(0,4),
m = str.substr(4,2),
d = str.substr(6,2);
return new Date(y,m,d);
}
Usage:
parse('20120401');
UPDATE:
As Rocket said, months are 0-based in js…use this if month’s aren’t 0-based in your string
function parse(str) {
if(!/^(\d){8}$/.test(str)) return "invalid date";
var y = str.substr(0,4),
m = str.substr(4,2) - 1,
d = str.substr(6,2);
return new Date(y,m,d);
}
UPDATE:
More rigorous checking for validity of date. Adopted HBP’s way to validate date.
function parse(str) {
var y = str.substr(0,4),
m = str.substr(4,2) - 1,
d = str.substr(6,2);
var D = new Date(y,m,d);
return (D.getFullYear() == y && D.getMonth() == m && D.getDate() == d) ? D : 'invalid date';
}