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Ajax Request

1. XMLHttpRequest

var xhr = new XMLHttpRequest();

xhr.open("get", "/api/test", true);

xhr.onreadystatechange = function() {

    if (xhr.readyState === 4 && xhr.status === 200) {

        var result = JSON.parse(xhr.responseText);

    }

}

xhr.send();


2. fetch

fetch("/api/test")

    .then(res => res.json())

    .then(data => console.log(data))


3. Axios (Using XMLHttpRequest)

axios.post(url)

axios.get(url, { params: opt }



Build a Mock Service in front-end

Mockjs

1) Install

npm install mockjs --save


if it is typescript, also should install: npm i --save-dev @types/mockjs


Mockjs can only hijack XMLHttpRequest, cannot hijack fetch


index.ts:

import Mock from "mockjs";

Mock.mock("/api/test", "get", () => {
return {
errno: 0,
data: {
name: `Yingxu${Date.now()}`,
},
};
});


import it from xx.tsx:

import "../_mock/index";
axios.get("/api/test").then((res) => console.log(res));


Then it will hijack XMLHttpRequest


Build a Mock Service in server side (node.js)

example:

const Mock = require('mockjs')

const Random = Mock.Random

module.export = [
{
url: '/api/question/:id',
method: 'get',
response() {
return {
errno: 0,
data: {
id: Random.id(),
title: Random.ctitle()
}
}
}
}
]


index.js

const Koa = require('koa')
const Router = require('koa-router')
const mockList = require('./mock/index')

const app = new Koa()
const router = new Router()

// register mock router
mockList.forEach(item => {
const { url, method, response} = item
router[method](url, async ctx => {
const res = response()
ctx.body = res
})

})

app.use(router.routes())
app.listen(3001)

then we can use nodemon index.js to start the service.

to mimic real situation, we can set 1s delay

async function getRes(fn) {
return new Promise(resolve => {
setTimeout(() => {
const res = fn()
resolve(res)
}, 1000)
})
}

// register mock router
mockList.forEach(item => {
const { url, method, response} = item
router[method](url, async ctx => {
const res = await getRes(response)
ctx.body = res
})

})

app.use(router.routes())
app.listen(3001)


跨域 (Cross Domain)

use devServer as proxy to visit mock service


1. install

npm i -D @craco/craco  


2. In root directory, create a new file:

craco.config.js

add the following content will redirect all the request related to /api to localhost:3001 

module.exports = {
devServer: {
proxy: {
"/api": "http://localhost:3001",
},
},
};



3. In package.json, revise the following:

"scripts": {
- "start": "react-scripts start"
+ "start": "craco start"
- "build": "react-scripts build"
+ "build": "craco build"
- "test": "react-scripts test"
+ "test": "craco test"
}


4. npm start



Deal with response error all together

create an ajax.ts

import axios from "axios";
import { message } from "antd";

const instance = axios.create({
timeout: 10 * 1000,
});

instance.interceptors.response.use((res) => {
const resData = (res.data || {}) as ResType;
const { errno, data, msg } = resData;

if (errno !== 0) {
// error tip
if (msg) {
message.error(msg);
}
throw new Error(msg);
}

return data as any;
});

export default instance;

export type ResType = {
errno: number;
data?: ResDataType;
msg?: string;
};

export type ResDataType = {
[key: string]: any;
};

for one service called question, we could create another file called question.ts

import axios from "./ajax";
import type { ResDataType } from "./ajax";

export async function getQuestionService(id: string): Promise<ResDataType> {
const url = `/api/question/${id}`;
const data = (await axios.get(url)) as ResDataType;
return data;
}

and then import { getQuestionService } from this file, and use as following:

useEffect(() => {
async function fn() {
const data = await getQuestionService(id);
console.log("edit page data", data);
}
fn();
}, []);


Define my own hooks to deal with loading status before getting the data

We should name each hook we define as useXXX.

For example, useLoadQuestionData.ts

import { useEffect, useState } from "react";
import { useParams } from "react-router-dom";
import { getQuestionService } from "../services/question";

function useLoadQuestionData() {
const { id = "" } = useParams();
const [loading, setLoading] = useState(true);
const [questionData, setQuestionData] = useState({});

useEffect(() => {
async function fn() {
const data = await getQuestionService(id);
setQuestionData(data);
setLoading(false);
console.log("edit page data", data);
}
fn();
}, []);

return { loading, questionData };
}

export default useLoadQuestionData;

then, we can retrieve by using const { loading, questionData } = useLoadQuestionData()


Use useRequest hook from ahooks

function useLoadQuestionData() {
const { id = "" } = useParams();
async function load() {
const data = await getQuestionService(id);
return data;
}

const { loading, data, error } = useRequest(load);
return { loading, data, error };
}

export default useLoadQuestionData;

then, can directly use loading, data, error:

const { loading, data, error } = useLoadQuestionData();

It will trigger automatically, however, you can trigger manually:

const {
loading,
run: handleCreateNew,
error,
} = useRequest(createQuestionService, {
manual: true,
onSuccess(result) {
message.success("创建成功");
nav(`/question/edit/${result.id}`);
},
});

Other components can trigger it by using run() function, here I rename it to be handleCreateNew():

onClick={handleCreateNew}


Request Data and refresh with url parameter change

async function loadAllList() {
const keyword = searchParams.get(LIST_SEARCH_PARAM_KEY) || "";
const data = await getQuestionListService({ keyword });
return data;
}
const { data, loading, error } = useRequest(loadAllList, {
refreshDeps: [searchParams],
});



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