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App Inventor 2 字典代码块 · App Inventor 2 中文网
...下需要使用字典？
A：列表能完成字典的绝大部分功能，不过字典具有比列表更好的查找性能，因此如果要对数据结构执行大量的操作，建议优先使用字典。
显示字典的常见方法是使用 JavaScript 对象表示法 (JSON)，例如：
{
"id...
How do you get the footer to stay at the bottom of a Web page?
...lt;/div>
<footer>
This is my footer
</footer>
NB:
1) The height of the header and footer must be known
2) Old versions of IE (IE8-) and Android (4.4-) don't support viewport units. (caniuse)
3) Once upon a time webkit had a problem with viewport units within a calc ru...
File Hash 扩展：文件哈希计算和 Base64 编码文件，sha256、sha512 哈希 ·...
...色 = 绿色
否则
设置 验证结果.文本 = "文件已修改或不完整"
设置 验证结果.背景颜色 = 红色
Base64 编码扩展
Base64 函数
Encode 编码(文本内容) {:.text}
将文本内容编码为 Base64 格式。
...
Retina displays, high-res background images
...
only screen and ( min-resolution: 2dppx) {
}
- Source
NB. This min--moz-device-pixel-ratio: is not a typo. It is a well documented bug in certain versions of Firefox and should be written like this in order to support older versions (prior to Firefox 16).
- Source
As @LiamNew...
常用Git命令汇总 - 开源 & Github - 清泛网 - 专注C/C++及内核技术
...作，所有一般在操作工作区的时候，直接删除了文件，而不是使用git rm的，最后提交是可以用这个，如下
#git commit -am "提交信息"
git commit -amend #修改最后一次提交的信息
#------------------------------------------
# 抛弃工...
Which commit has this blob?
...), and commit 91904f5, commit 2deda00 (02 Nov 2017) by Stefan Beller (stefanbeller).
(Merged by Junio C Hamano -- gitster -- in commit 556de1a, 28 Dec 2017)
builtin/describe.c: describe a blob
Sometimes users are given a hash of an object and they want to
identify it further (ex.: Use v...
vs vs for inline and block code snippets
...odenza {display:block;white-space:pre-wrap}
</style>`
Testing:
(NB: the following is a scURIple utilizing a data: URI protocol/scheme, therefore the %0A nl format codes are essential in preserving such when cut and pasted into the URL bar for testing - so view-source: (ctrl-U) looks good ...
Oracle PL/SQL - How to create a simple array variable?
... dbms_output.put_line(array(i));
end loop;
end;
Or TABLE for an unbounded array:
...
type array_t is table of varchar2(10);
...
The word "table" here has nothing to do with database tables, confusingly. Both methods create in-memory arrays.
With either of these you need to both ini...
Why is rbindlist “better” than rbind?
...m v1.9.3. The data set consists of 10000 data.frames each of size 10*500.
NB: this benchmark has been updated to include a comparison to dplyr's bind_rows
library(data.table) # 1.11.5, 2018-06-02 00:09:06 UTC
library(dplyr) # 0.7.5.9000, 2018-06-12 01:41:40 UTC
set.seed(1L)
names = paste0("V", 1:5...
Python's many ways of string formatting — are the older ones (going to be) deprecated?
...
NB. I didn't argue that the old style is better in all respects - just that it is shorter and sometimes more readable (and sometimes not). Certainly the new way is much more flexible.
– jsbueno
...