易截截图软件、单文件、免安装、纯绿色、仅160KB

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 获取对象的高度和宽度详细说明

scrollHeight: 获取对象的滚动高度。
scrollLeft:设置或获取位于对象左边界和窗口中目前可见内容的最左端之间的距离
scrollTop:设置或获取位于对象最顶端和窗口中可见内容的最顶端之间的距离
scrollWidth:获取对象的滚动宽度
offsetHeight:获取对象相对于版面或由父坐标 offsetParent 属性指定的父坐标的高度
offsetL ......

JavaScript中的空类型

转载理由:短小精悍。
来源:互联网
一 Undefined 类型
只有一种值 undefined
以下三种情况typeof 返回类型为undefined
1. 当变量未初始化时
2. 变量未定义时
3. 函数无明确返回值时(函数没有返回值时返回的都是undefined)
undefined 并不等同于未定义的值
typeof 并不真正区分是否是未定义
看以下示例 ......

C#后台调用前台javascript的五种方法


由于项目需要,用到其他项目组用VC开发的组件,在web后台代码无法访问这个组件,所以只好通过后台调用前台的javascript,从而操作这个组件。在网上找了找,发现有三种方法可以访问到前台代码:
第一种,OnClientClick    (vs2003不支持这个方法)
<asp:Button ID="Button1" runat="se ......

JavaScript类型判断

在JavaScript中,变量中可以存储的值主要有两种类型:原始值(primitive value)和引用值(reference value)。前者通常是固定而又简单的数据,存储在栈(stack)中,而后者则是比较大的对象,存储在堆(heap)中,而对于后者的调用,是通过存储在栈中的指针来完成的。原始类型有五种:Number、String、Boolean、Null和Unde ......
© 2009 ej38.com All Rights Reserved. 关于E健网联系我们 | 站点地图 | 赣ICP备09004571号