javascript parseInt is broken
javascript parseInt is broken
I was debugging some strange errors in a date conversion function I was writing, and I stumbled upon something that amazed me... a strange bug in parseInt
>>>parseInt('06')
6
>>>parseInt('07')
7
>>>parseInt('08')
0
>>>parseInt('09')
0
>>>parseFloat('08')
8
>>>parseFloat('09')
9
Clearly for the strings '08' and '09' parseInt fails to return the right value. One workaround is easy, use parseFloat.
Why does this happen and where should I report this? I find it extremely odd that it happens in both Firefox and Internet Explorer 6 & 7; there must be some explanation right?
You can test it out for yourself using the FireBug javascript console), or by using one of these two links
alert(parseInt('07')+' == 7 ?')
alert(parseInt('08')+' == 8 ?')
Ok, Ok, so now that I explained how you would expect it to work (and clearly how I expected it to work) I'm going to answer my own question (yes I hate it when I do that too)
The problem is with how parseInt guesses the base of your number. Read the parseInt spec. Instead of always defaulting to base 10, it tries to guess, and if the first character is '0' it thinks you want to parse as an octal number, and if it starts with '0x' it thinks you want hexadecimal.
So, the solution is either to use parseFloat or to always specify your base.
Defaults that change on their own can't be trusted.
>>>parseInt('08',10)
8
相关文档:
javascript中的null和undefined
本文装载网络,版权归原作者所有。
null :表示无值;
undefined : 表示一个未声明的变量,
或已声明但没有赋值的变量,
&nb ......
代码示例
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=gb2312" />
<title>无标题文档</title>
</head>
<mce:style><!--
.man{ float:left; background:#9af; margin:3px; padding:3px; cursor:default}
--></mce:style>< ......
尽管 JavaScript 历史上使用冗长而令人生厌的代码块来标的特定浏览器的时期已经结束了,但是偶尔使用一些简单的代码块和对象检测来确保一些代码在用户机器上正常工作依然是必要的。
这篇文章中,我会略述一下 Internet Explorer 和 Firefox 在 JavaScript 语法上不同的几 个方面。
......
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<meta http-equiv="X-UA-Compatible" content="IE=EmulateIE7" />
<title>滚动新闻类</title>
<style type="text/css">
body {
  ......
<html>
<body>
<SCRIPT type="text/javascript">
<!--
var target=[]
var time_id=[]
function ShowDateTime(){
setTimeout("ShowDateTime()", 1000);
for (var i=0,j=target.length;i<j;i++)
{
var today=new Date();
timeo ......