nodejs渐入佳境[9]-保存节点到json文件

const yargs = require('yargs');
const nodes = require('./nodes.js')
console.log('Start app.');

console.log(process.argv);

console.log('yargs',yargs.argv);
const argv = yargs.argv;
var command = process.argv[2];

if(command==='add'){
  nodes.addNote(argv.title,argv.body);
}else if(command === 'list'){
  nodes.getAll();

}else if(command =='read'){
  nodes.getNote(argv.title);
}else if(command=='remove'){
  nodes.removeNote(argv.title);
}else{
  console.log('command not find');
}

console.log('start nodes.js');
const fs = require('fs');
var addNote = (title,body)=>{
  var notes = [];
  var note = {
      title,
      body
  };

  try{
    //读取json文件，读出来是string
    var notesString = fs.readFileSync('notes-data.json');
    // string转换为json对象
    notes = JSON.parse(notesString);
  }catch(e){

  }
  //增加
  notes.push(note);
  //保存
  fs.writeFileSync('notes-data.json',JSON.stringify(notes));
}

var getAll = ()=>{
console.log('Get All notes');
};

var getNote = (title)=>{

  console.log('getting note',title);
};

var removeNote = (title)=>{
  console.log('Removing note',title);
};

module.exports = {
    addNote,
    getAll,
    getNote,
    removeNote
};

> node app.js add --title="buy book2" --body="jonson"

> node app.js add --title="buy book2" --body="jonson"

[{"title":"buy book2","body":"jonson"},{"title":"buy book2","body":"jonson"}]

console.log('start nodes.js');
const fs = require('fs');
var addNote = (title,body)=>{
  var notes = [];
  var note = {
      title,
      body
  };

  try{
    var notesString = fs.readFileSync('notes-data.json');
    notes = JSON.parse(notesString);
  }catch(e){

  }

  //筛选出相同的节点
  var duplicateNotes = notes.filter((note)=>note.title===title);
  //没有相同的节点
  if(duplicateNotes.length ===0){
    notes.push(note);
    fs.writeFileSync('notes-data.json',JSON.stringify(notes));
  }


}

var getAll = ()=>{
console.log('Get All notes');
};

var getNote = (title)=>{

  console.log('getting note',title);
};

var removeNote = (title)=>{
  console.log('Removing note',title);
};

module.exports = {
    addNote,
    getAll,
    getNote,
    removeNote
};

> node app.js add --title="buy book2" --body="jonson"