Dates serialize to ISO format. ISO date string deserialize to Dates when `dynamicTyping` is true.

papaparse.js

@@ -410,6 +410,9 @@
 			if (typeof str === 'undefined' || str === null)
 				return '';
 
+			if (str.constructor === Date)
+				return JSON.stringify(str).slice(1, 25);
+
 			str = str.toString().replace(quoteCharRegex, _quoteChar + _quoteChar);
 
 			var needsQuotes = (typeof _quotes === 'boolean' && _quotes)
@@ -956,6 +959,7 @@
 	{
 		// One goal is to minimize the use of regular expressions...
 		var FLOAT = /^\s*-?(\d*\.?\d+|\d+\.?\d*)(e[-+]?\d+)?\s*$/i;
+		var ISO_DATE = /(\d{4}-[01]\d-[0-3]\dT[0-2]\d:[0-5]\d:[0-5]\d\.\d+([+-][0-2]\d:[0-5]\d|Z))|(\d{4}-[01]\d-[0-3]\dT[0-2]\d:[0-5]\d:[0-5]\d([+-][0-2]\d:[0-5]\d|Z))|(\d{4}-[01]\d-[0-3]\dT[0-2]\d:[0-5]\d([+-][0-2]\d:[0-5]\d|Z))/;
 
 		var self = this;
 		var _stepCounter = 0;	// Number of times step was called (number of rows parsed)
@@ -1131,12 +1135,12 @@
 					return true;
 				else if (value === 'false' || value === 'FALSE')
 					return false;
-				else if(FLOAT.test(value)) {
+				else if (FLOAT.test(value))
 					return parseFloat(value);
-				}
-				else {
+				else if (ISO_DATE.test(value))
+					return new Date(value);
+				else
 					return (value === '' ? null : value);
-				}
 			}
 			return value;
 		}

tests/test-cases.js

@@ -885,6 +885,15 @@ var PARSE_TESTS = [
 			errors: []
 		}
 	},
+	{
+		description: "Dynamic typing converts ISO date strings to Dates",
+		input: 'ISO date,long date\r\n2018-05-04T21:08:03.269Z,Fri May 04 2018 14:08:03 GMT-0700 (PDT)\r\n2018-05-08T15:20:22.642Z,Tue May 08 2018 08:20:22 GMT-0700 (PDT)',
+		config: { dynamicTyping: true },
+		expected: {
+			data: [["ISO date", "long date"], [new Date("2018-05-04T21:08:03.269Z"), "Fri May 04 2018 14:08:03 GMT-0700 (PDT)"], [new Date("2018-05-08T15:20:22.642Z"), "Tue May 08 2018 08:20:22 GMT-0700 (PDT)"]],
+			errors: []
+		}
+	},
 	{
 		description: "Blank line at beginning",
 		input: '\r\na,b,c\r\nd,e,f',
@@ -1435,6 +1444,11 @@ var UNPARSE_TESTS = [
 		input: [{"Col1": "a", "Col2": "b", "Col3": "c"}, {"Col1": "d", "Col2": "e", "Col3": "f"}],
 		config: {header: false},
 		expected: 'a,b,c\r\nd,e,f'
+	},
+	{
+		description: "Date handling",
+		input: [{date: new Date("2018-05-04T21:08:03.269Z"), "not a date": 16}, {date: new Date("Tue May 08 2018 08:20:22 GMT-0700 (PDT)"), "not a date": 32}],
+		expected: 'date,not a date\r\n2018-05-04T21:08:03.269Z,16\r\n2018-05-08T15:20:22.000Z,32'
 	}
 ];