Type detection using PropTypes
React.PropTypes.string.isRequireCheck whether name is a string and is required.When invalid values are provided for prop, a warning is displayed in the JavaScript console.MyComponent.propTypes = {/ / you can define one.jsThe original type of prop, by default, is optional.OptionalArray: React.PropTypes.array,
optionalBool: React.PropTypes.bool,
optionalFunc: React.PropTypes.func,
optionalNumber: React.PropTypes.number,
optionalObject: React.PropTypes.object,
optionalString: React.PropTypes.string,
optionalSymbol: React.PropTypes.symbol,
// Anythin...
Type check
import PropTypes from 'prop-types'
Class name = = = = =List
List.propTypes = {
list: PropTypes.array
}
// Default valueList.defaultProps = {
list:[]
}
props:
1.Read-only cannot be modified (no longer assigns expression to the left).2.ComponentWillReceiveProp()
3.propTypes
4. defaultProps
5.children
web > native
native You need to download the installation package.// react-router-dom
web Direct//react-router-native
nvm
command
Explain
nvm list available
View all versions
nvm install version number
download
nvm list
List the currently ava...
React assembly
Custom components
1、We can use functions to define a component:FunctionHelloMessage(props) {
return <h1>Hello World!</h1>;
}
You can also use it.ES6 class To define a component:class Welcome extends React.Component {
render() {
return <h1>Hello World!</h1>;
}
}
2.const element = <HelloMessage /> User defined components.Attention, nativeHTML The element name begins with a lowercase letter and is customized.React The class name begins with capitals, for example.HelloMessage It can't be written as helloMessage. In addition, we need...
Reactfunction
React
function
1
ReactIt is a JavaScript library for building user interfaces.
2
ReactIt is mainly used to build UI. Many people think React is V (view) in MVC.
3
React The internal project originated from Facebook, which is used to erect Instagram website and opened in May 2013.
4
React With high performance, code logic is very simple, and more and more people are paying attention to it and using it.
Characteristic
Characteristic
introduce
Declarative design
ReactUsing the declarative paradigm, you can easily describe applications.
High efficiency
R...
Title Description
Find the first character that appears only once in a string (0< = string length < = 10000, all made up of letters) and return its position, if not – 1 (case sensitive)
thinking
Traversing the string, find the value of the first count count 1 and return its subscript value.
Answer
class Solution:
def FirstNotRepeatingChar(self, s):
# write code here
if not s or len(s)>10000:
return -1
else:
for i in s:
if s.count(i) == 1:
return s.index(i)
I. what is an interface?
Interface testing is mainly used to define specific interaction points between external systems and systems as well as between internal subsystems, and then through these interaction points, through a number of special rules, that is, protocols, to interact between data.
Two. What types of interfaces are there?
Interfaces are generally divided into two categories:
1.Internal interface of program
2.System external interface
System external interface: for example, if you want to get resources or information from other websites or servers, others will not share the dat...
85branch
1 #include<iostream>
2 #include<cstdio>
3 #include<queue>
4 #include<cmath>
5 using namespace std;
6 typedef long long ll;
7 typedef pair<ll,int>pii;
8 const int maxn=1e5+7;
9 const int maxm=7*1e6+7;
10 priority_queue<int>q;
11 int n,m,qq,u,v,t;
12 int pup_top,lat_top;
13 ll a[maxn],pup[maxm],lat[maxn];
14 double p;
15 int main(){
16 cin>>n>>m>>qq>>u>>v>>t;
17 p=(double)u/v;
18 for(int i=1;i<=n;i++){
19 cin>>a[i];
20 q.push(a[i]);
21 }
22 for(int i=1;i<=m...
1.Definition
2.test questions
