Implementation method of Express middleware body-parser

The content of this article is about the implementation method of Express middleware body-parser. It has certain reference value. Friends in need can refer to it. I hope it will be helpful to you.

The previous article wrote about how to use body-parser middleware to process post requests. Today I will roughly implement the urlencoded method in body-parser.
First enter mkdir lib && cd lib through the command prompt.
Enter touch body-parser.js.
Type the following code in body-parser.js.

// lib/body-parser.js
const querystring = require('querystring');

module.exports.urlencoded = function (req, res, next) {
    let chunks = [];
    req.on('data', data => {
        chunks.push(data);
    });

    req.on('end', () => {
        // 合并Buffer。
        let buf = Buffer.concat(chunks).toString();
        // 把querystring解析过的json 放到 req.body上。
        req.body = querystring.parse(buf);
        next();
    });
}

The following is the main program code.

// app.js
const express = require('express');
const bodyParser = require('./lib/body-parser');

let app = express();

app.use(bodyParser.urlencoded);


app.post('/', (req, res) => {
    res.send(req.body);
});

app.listen(8000);

Now we have completed the function similar to the body-parser middleware. Req.body has the requested post data.

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