大约有 46,000 项符合查询结果（耗时：0.0616秒） [XML]
In JavaScript, why is “0” equal to false, but when tested by 'if' it is not false by itself?
...you explicitly do "0" == false, both sides are being converted to numbers, and then the comparison is performed.
When you do: if ("0") console.log("ha"), the string value is being tested. Any non-empty string is true, while an empty string is false.
Equal (==)
If the two operands are not o...
How to reliably open a file in the same directory as a Python script
...ame directory as the currently running Python script by simply using a command like
5 Answers
...
How do I get the height and width of the Android Navigation Bar programmatically?
...lack navigation bar on the bottom of the screen is not easily removable in Android. It has been part of Android since 3.0 as a replacement for hardware buttons. Here is a picture:
...
Getting the first character of a string with $str[0]
I want to get the first letter of a string and I've noticed that $str[0] works great. I am just not sure whether this is 'good practice', as that notation is generally used with arrays. This feature doesn't seem to be very well documented so I'm turning to you guys to tell me if it's all right –...
How to create a UIView bounce animation?
...
With iOS7 and UIKit Dynamics, there is no longer any need to use CAKeyframeAnimations or UIView animations!
Take a look at Apple's UIKit Dynamics Catalog app. Alternately, Teehanlax has a clear, concise tutorial with the full project ...
How to plot two histograms together in R?
I am using R and I have two data frames: carrots and cucumbers. Each data frame has a single numeric column which lists the length of all measured carrots (total: 100k carrots) and cucumbers (total: 50k cucumbers).
...
Why can't I center with margin: 0 auto?
I have a #header div that is 100% width and within that div I have an unordered list. I have applied margin: 0 auto to the unordered list but it won't center it within the header div.
...
How should I validate an e-mail address?
...chnique for validating an e-mail address (e.g. from a user input field) in Android? org.apache.commons.validator.routines.EmailValidator doesn't seem to be available. Are there any other libraries doing this which are included in Android already or would I have to use RegExp?
...
How do I represent a hextile/hex grid in memory?
...Amit Patel has posted an amazing page on this topic. It's so comprehensive and wonderful that it needs to be the definitive answer to this question: Hexagonal Grids
share
|
improve this answer
...
In javascript, is an empty string always false as a boolean?
...
Yes. Javascript is a dialect of ECMAScript, and ECMAScript language specification clearly defines this behavior:
ToBoolean
The result is false if the argument is the empty String (its length is zero);
otherwise the result is true
Quote taken from http://www.ecma-inte...