nodejs渐入佳境[11]-yargs获取用户输入高级用法
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yargs高级用法,用于输出帮助信息,缩写提示等。
app.js:
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| const yargs = require('yargs'); const nodes = require('./nodes.js')
const argv = yargs .command('add','add a new note',{ title:{ describe:'Title of note', demand:true, alias:'t' }, body:{ describe:'Body of note', demand:true, alias:'b' } }) .command('list','List all notes') .command('read','Read a note',{ title:{ describe:'Title of note', demand:true, alias:'t' } }) .command('remove','Remove a note',{ title:{ describe:'Title of note', demand:true, alias:'t' } }) .help() .argv; var command = process.argv[2];
if(command==='add'){ var note = nodes.addNote(argv.title,argv.body); if(note){ console.log('add success'); console.log(`title:${note.title}`); console.log(`body:${note.body}`); } }else if(command === 'list'){ var allnotes = nodes.getAll(); allnotes.forEach((note)=>{ console.log(note)}); }else if(command =='read'){ var note = nodes.getNote(argv.title); if(note){ console.log('find'); console.log(`title:${note.title}`); console.log(`body:${note.body}`); }else{ console.log('note not found'); } }else if(command=='remove'){ var noteRemoved = nodes.removeNote(argv.title); var message = noteRemoved?'Note was removed':'note not found'; console.log(message); }else{ console.log('command not find'); }
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nodes.js
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| console.log('start nodes.js'); const fs = require('fs');
var fetchNode = ()=>{ try{ var notesString = fs.readFileSync('notes-data.json'); return JSON.parse(notesString); }catch(e){ return []; } }
var saveNote = (notes)=>{
fs.writeFileSync('notes-data.json',JSON.stringify(notes));
}
var addNote = (title,body)=>{ var notes = fetchNode(); var note = { title, body };
var duplicateNotes = notes.filter((note)=>note.title===title); if(duplicateNotes.length ===0){ notes.push(note); saveNote(notes); return note; } }
var getAll = ()=>{ var notes = fetchNode(); return notes; };
var getNote = (title)=>{
var notes = fetchNode(); var duplicateNotes = notes.filter((note)=>note.title===title); return duplicateNotes[0]; };
var removeNote = (title)=>{ var notes = fetchNode(); var duplicateNotes = notes.filter((note)=>note.title!==title); saveNote(duplicateNotes); return notes.length !==duplicateNotes.length; };
module.exports = { addNote, getAll, getNote, removeNote };
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测试
打开控制台,在当前目录下输入:
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| > node app.js add --help
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控制台返回结果:
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| app.js add
add a new note
选项: --version 显示版本号 [布尔] --help 显示帮助信息 [布尔] --title, -t Title of note [必需] --body, -b Body of note [必需]
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输入:
控制台返回结果:
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| app.js [命令]
命令: app.js add add a new note app.js list List all notes app.js read Read a note app.js remove Remove a note
选项: --version 显示版本号 [布尔] --help 显示帮助信息 [布尔]
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