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javascript set a variable if undefined
...efined. It would therefore not only match undefined but also null, false, 0, NaN, "" (but not "0").
If you want to set to default only if the variable is strictly undefined then the safest way is to write:
var x = (typeof x === 'undefined') ? your_default_value : x;
On newer browsers it's actu...
Replace a value if null or undefined in JavaScript
...
Here’s the JavaScript equivalent:
var i = null;
var j = i || 10; //j is now 10
Note that the logical operator || does not return a boolean value but the first value that can be converted to true.
Additionally use an array of objects instead of one single object:
var options = {
...
How to calculate a logistic sigmoid function in Python?
... math.exp(-x))
And now you can test it by calling:
>>> sigmoid(0.458)
0.61253961344091512
Update: Note that the above was mainly intended as a straight one-to-one translation of the given expression into Python code. It is not tested or known to be a numerically sound implementation. I...
php中json_decode()和json_encode()的使用方法 - 更多技术 - 清泛网 - 专注C/C++及内核技术
...de()和json_encode()的使用方法1.json_decode()json_decode(PHP 5 >= 5.2.0, PECL json >= 1.2.0)json_decode — 对 JSON 格式的字符串进行编码说明mixed jso...1.json_decode()
(PHP 5 >= 5.2.0, PECL json >= 1.2.0)
对 JSON 格式的字符串进行编码
说明：
mixed json_decode ...
Numpy how to iterate over columns of array?
...
– Ibrahim Muhammad
Sep 23 '13 at 17:08
49
For those wondering, array.T isn't costly, as it just c...
JavaScript + Unicode regexes
...
205
Situation for ES 6
The upcoming ECMAScript language specification, edition 6, includes Unicode-...
How do I install the OpenSSL libraries on Ubuntu?
I'm trying to build some code on Ubuntu 10.04 LTS that uses OpenSSL 1.0.0. When I run make, it invokes g++ with the "-lssl" option. The source includes:
...
How can I convert an RGB image into grayscale in Python?
...
320
How about doing it with Pillow:
from PIL import Image
img = Image.open('image.png').convert('LA...
Clear icon inside input text
...ch" to your input
The support is pretty decent but will not work in IE<10
<input type="search">
Clearable input for old browsers
If you need IE9 support here are some workarounds
Using a standard <input type="text"> and some HTML elements:
/**
* Clearable text ...
Declaring variables inside or outside of a loop
...
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