Take a look at the source code:
Date.prototype.toJSON = function( ) {
return '"' this.getUTCFulYear() '-'
(this.getUTCMonth() 1).toPaddedString(2) '-'
this.getUTCDate().toPaddedString(2) ' T'
this.getUTCHours().toPaddedString(2) ':'
this.getUTCMinutes().toPaddedString(2) ':'
this.getUTCSeconds().toPaddedString(2) 'Z" ';
};
actually returns the JSON string of Date. An example is given below:
new Date(1969, 11, 31, 19).toJSON();
//-> '"1969-12-31T19: 00:00"'