Some Archives - Simon Technology Blog

ReactJS – The valid React element (or NULL) must be returned. You may have returned undefined, array, or other invalid objects

I am new to ReactJS and I have a problem. I can’t solve it. Everything seems to be fine, but the console still lets me:

A valid React element (or null) must be returned. You may have
returne

October 21, 2021By Simo React Arrays, can, Elements, invalid, must, null, object, Other, React, Reactjs, return, Some, undefined, valid, You canLeave a Comment

Some summary about Flex

How to turn a box into a flexible box?

1. Define the attributes of a flexible box:

display:flex–>This attribute defines a flexible box.

flex:-direction:row–>Define the direction

October 20, 2021By Simo Flex About, Flex, Some, SummaryLeave a Comment

Some basic contents of CSS

The best way to clear floats (add this attribute to the parent element) .clearfix::after {content: “”; display: block; clear: both;} Select The first bit in the side-by-side element is set to this

October 19, 2021By Simo CSS Content, CSS, foundation, SomeLeave a Comment

Regular expression – GREP: How to search for, but simultaneously exclude some match

I need a way to simplify this command:

grep’SEARCHTERM’ server.log | grep -v ‘ PHHIABFFH’ | grep -v’Stats’ It should find all rows including SEARCHTERM, but exclude if one of the SEARCHTERM r

October 17, 2021By Simo Regexp and simultaneous, exclude, expression, GREP, How, match, regular, search, Some, valueLeave a Comment

Create import export of Linux database and some basic instructions

First check mysql related directories under linux

Execute query SQL< /p> mysql>show variables like ‘%dir%’;

datadir is the data path

The running path is determined, and the impo

October 16, 2021By Simo Linux and, Basic, creation, database, export, import, instruction, linux, SomeLeave a Comment

SED practice, some SED common methods

1. Copy the /etc/rc.d/rc.local file to the /tmp directory, and copy the
Add # at the beginning of lines that start with at least one blank character. sed -ri’s/^ +/#/g’ rc.local 2. Copy /bo

October 16, 2021By Simo Linux common, method, practice, Sed, SomeLeave a Comment

[Linux Shell] CentOS Some use shell management commands Collection (1) Continuous update

Check the system version rpm -q centos-release

View the kernel
uname -r
View the top 10 processes currently occupying the largest memory
ps aux |sort -nrk 4 |head -n 10
View the top 10 proce

October 15, 2021By Simo Centos centos, collection, Command, continuous, easy to use, Linux Shell, management, one, shell, Some, UpdateLeave a Comment

His longeting some HBase useful tools and features

1. HBase stores pictures, documents and other byte stream content

https://issues.apache.org/jira/browse/HBASE-11339

2. Speed control of compact

https://issues.apache.org/jira/br

October 12, 2021By Simo Hadoop Features, HBase, Long-term, Some, tools, updated, usefulLeave a Comment

Ruby-on-rails – Dynamic `named_scope` depends on some standards

Dear, I have a student model, I have specified some name_scopes in it, such as from_program, from_year, from_school, has_status, from_course, etc…

Anyway, can I dynamically link different n

October 6, 2021By Simo Ruby Dynamics, Named, rails, ruby, Scope depends on, Some, StandardLeave a Comment

Delphi – Tregistry – Why is some keys readable and some keys are not available?

I wrote the following code:

var
MainForm: TMainForm;
const
SRootKey = HKEY_LOCAL_MACHINE;
SKey =’SOFTWARE\Microsoft\Windows NT\CurrentVersion\NetworkList\Profiles’;
implementation
{$ R *.d

October 5, 2021By Simo Delphi Delphi, key, not, readable, Some, somewhat, Tregistry, whyLeave a Comment