nodeJs read file, write file

var fs = require('fs');

//读取文件并写入内容
fs.readFile('./tt.txt', 'utf-8', function(err, data) {
    
    
    console.log(err, data);
    data += "dfddf大方豆腐";
    fs.writeFile('./tt.txt', data, function(err) {
    
    
        console.log(err);
        if (!err) {
    
    
            console.log("写入成功");
        }
    })
})

Effect: