【Node.js】 コンソール（CLI）で進捗をプログレスバー表示してみる

  // maxCount : 進捗100%のときの数値
  // progressLength : 進捗(■と□)の合計数
  // title : 進捗の前に表示するタイトル
const simpleProgress = (maxCount,progressLength,title)=>{
    let nowCount = 0;

    return  addCount =>{
        nowCount += addCount;

        const per = Math.min( nowCount / maxCount , 1.0 );
        const count = nowCount <= 0 ? 0 : Math.floor(per * progressLength );

        process.stdout.write( `${ title }【${
            "■".repeat( count ) + "□".repeat( progressLength - count)
        }】${ Math.floor(per * 100) }%\r` );
        return per >= 1;
    };
};

const simpleProgress = (maxCount,progressLength,title)=>{
    let nowCount = 0;
    let dispCount = 0;

    const dispChar = [ "｜","／","―","＼"];

    return  addCount =>{
        nowCount += addCount;

        const per =  nowCount / maxCount ;
        process.stdout.write( `${ title } ${ dispChar[dispCount] } ... ${ Math.floor(per * 100) }%\r`);
        dispCount = ++dispCount >= dispChar.length ? 0 : dispCount;

        return per >= 1;
    };
};

    // カーソルの非表示・終了時のカーソル復帰
process.stdout.write( "\x1b[?25l" );
process.on("exit", ()=>process.stdout.write( "\x1b[?25h" ));
process.on("SIGINT", ()=>process.exit(0));

const progress = simpleProgress( 500 , 20 ,"進捗状況" );

console.log( "処理を開始しました。" );
progress(0);

const timerFunc = ()=>{
    const step = Math.floor(Math.random() * 20) + 10;
    if( progress(step) === true ) {
        process.stdout.write("\n終了しました");
        return;
    }
    setTimeout( timerFunc , 100 );
};
setTimeout( timerFunc , 100 );

const multiProgress = ()=>{
    let endLine = 0;

    const progressMap = new WeakMap();
    const progressBody = function (){};
    progressBody.prototype={
        addCount:  function(count){ return progressText( count , this )},
        reset:  function() {
            progressText( 0  , this ,true);
            return this;
        }
    };

    const createProgress = ( maxCount,progressLength , label )=>{
        const p = new progressBody();
        progressMap.set( p , {
            maxCount:maxCount,progressLength:progressLength,label:label,
            nowCount:0,line:endLine,
        });
        process.stdout.write( "\n" );
        endLine++;
        return p.reset();
    };

    const progressText = (addCount,progressObj,resetFlg = false)=>{
        const p = progressMap.get( progressObj );
        const lineUp = endLine - p.line; // カーソルの移動量
        const nowCount = resetFlg ? (p.nowCount = 0 ) : ( p.nowCount += addCount );

        const per = Math.min( nowCount / p.maxCount , 1.0 );
        const dispCount = nowCount <= 0 ? 0 : Math.floor(per * p.progressLength );

        process.stdout.write( `\x1b[${ lineUp }F` ); // カーソルUP
        if( resetFlg ) process.stdout.write( "\x1b[2K" ); // 行消去
        process.stdout.write( `${ p.label }【${
            "■".repeat( dispCount ) + "□".repeat( Math.max(p.progressLength - dispCount,0))
        }】${ Math.floor(per * 100) }%\r` );
        process.stdout.write( `\x1b[${ lineUp }E` ); // カーソルDOWN
        return per >= 1;
    };

    return  {
        writeMessage:message => {
            process.stdout.write( message );process.stdout.write( "\n" );
            endLine ++;
        },
        addProgress:( maxCount,progressLength , label )=>createProgress(maxCount,progressLength , label),
    };
};

process.stdout.write( "\x1b[?25l" );
process.on("exit", ()=>process.stdout.write( "\x1b[?25h" ));
process.on("SIGINT", ()=>process.exit(0));

const progress = multiProgress(  );

progress.writeMessage( "処理を開始しました。" );
const progressMain = progress.addProgress( 500 , 15 , "メイン処理：" );
progress.writeMessage( "サブの進捗状況" );
const progressSub = progress.addProgress( 500 , 20 , "サブ処理：" );

const timerFunc = ()=>{
    const step = Math.floor(Math.random() * 20) + 10;
    if( progressSub.addCount(step) === true ) {
        const stepMain = Math.floor(Math.random() * 300) + 100;
        if( progressMain.addCount(stepMain) === true ) {
            process.stdout.write("\n終了しました");
            return ;
        }
        progressSub.reset();
    }
    setTimeout( timerFunc , 100 );
};
setTimeout( timerFunc , 100 );