Constructor
new DateString(value)
    A String whose value is a valid representation of a Date.
Use this type if you need to preserve the format of the value and still
check if it's valid.
Example:
```js
var loopback = require('loopback');
var dt = new loopback.DateString('2001-01-01');
dt.toString();
// '2001-01-01'
dt._date.toISOString();
// '2001-01-01T00:00:00.000Z'
```
You can use this definition on your models as well:
```json
{
  "name": "Person",
  "base": "PersistedModel",
  "properties": {
    "name": {
      "type": "string"
    },
    "dob": {
      "type": "DateString",
      "required": true
    },
  },
  "validations": [],
  "relations": {},
  "acls": [],
  "methods": {}
}
```
    Parameters:
| Name | Type | Description | 
|---|---|---|
value | 
            
            String | 
- Source:
 
Methods
toJSON() → {String}
    Returns the JSON representation of the DateString object.
- Source:
 
Returns:
    A JSON string.
- Type
 - String
 
toString() → {String}
    Returns the value of DateString in its original form.
- Source:
 
Returns:
    The Date as a String.
- Type
 - String