Closed Bug 288218 Opened 20 years ago Closed 20 years ago

Using the JavaScript Date's setMonth(month-1) function doesn't work correctly

Categories

(Firefox :: General, defect)

Product:
Firefox
Component:
General
Platform:
x86
Windows XP
Type:
defect
Priority:
Not set
Severity:
normal

Tracking

()

Status:
RESOLVED INVALID

People

(Reporter: kenevel, Assigned: bugzilla)

Details

User-Agent:       Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.7.6) Gecko/20050317 Firefox/1.0.2
Build Identifier: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.7.6) Gecko/20050317 Firefox/1.0.2

Save the following to a temporary HTML file and view in Firefox

<html>
<head>
<script type="text/javascript">
	function start(){
		var date = new Date();
		date.setFullYear(2005);
		date.setMonth(2-1);// Feb
		date.setDate(5);
		document.body.appendChild(document.createTextNode(date.toString()));
		document.body.appendChild(document.createElement("BR"));
		date.setMonth(3-1);// March
		document.body.appendChild(document.createTextNode(date.toString()));
		document.body.appendChild(document.createElement("BR"));
		date = new Date(2005,2-1,5); // February
		document.body.appendChild(document.createTextNode(date.toString()));
	}
</script>
<body onload="start()">
</body>
</html>

The output is as follows: 

Sat Mar 05 2005 00:19:02 GMT+0000 (GMT Standard Time)
Sat Mar 05 2005 00:19:02 GMT+0000 (GMT Standard Time)
Sat Feb 05 2005 00:00:00 GMT+0000 (GMT Standard Time)

However, line 1 is incorrect - it should be February, not March, as in the last
line. 

Reproducible: Always

Steps to Reproduce:
1. No special setup steps, please see the bug details for sample JS/HTML required

Actual Results:  
Please see the details section

Expected Results:  
Please see the details section

Great browser, keep up the good work :)
> 		var date = new Date();

Wed Mar 30 2005 02:44:31 GMT+0300 (EEST)

> 		date.setFullYear(2005);

Wed Mar 30 2005 02:44:31 GMT+0300 (EEST)

> 		date.setMonth(2-1);// Feb

February 30th 2005 -> March 2nd 2005
Wed Mar 02 2005 02:44:31 GMT+0200 (EET)

> 		date.setDate(5);

Sat Mar 05 2005 02:44:31 GMT+0200 (EET)

> 		date.setMonth(3-1);// March

Sat Mar 05 2005 02:44:31 GMT+0200 (EET)

> 		date = new Date(2005,2-1,5); // February

Sat Feb 05 2005 00:00:00 GMT+0200 (EET)

Looks ok.
Status: UNCONFIRMED → RESOLVED
Closed: 20 years ago
Resolution: --- → INVALID
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