array.push（）にはループの最終値のみが含まれています

Question

次のJavaScript（Typescript）サンプルがあります。ここでは、配列を初期化し、endタイムスタンプが範囲に含まれるまで1時間ごとのタイムスタンプを押します。ループからのconsole.logは期待値をログアウトする。

ループ2017-03-27T18：00：00 + 01：00

ループ2017-03-27T19：00：00 + 01：00

ループ2017-03-27T20：00 ：00 + 01：00

ただし、結果の配列には正しい数のレコードしか含まれていないようですが、すべて最終値です。

結果2017-03-28T18：00：00 + 01：00

結果2017-03-28T18：00：00 + 01：00

これはなぜでしょうか？

Answer 1

MomentJSオブジェクトは、状態の変更可能（変更可能）なオブジェクトです。 MomentJSオブジェクトでaddを呼び出すと、それが変更されますが、新しいオブジェクトは作成されません。同じオブジェクトへの参照を返します。オブジェクト

 
    +−−−−−−−−−+   
res−>| (array) |   
    +−−−−−−−−−+  +−−−−−−−−−−+  
    | 0  |−−−−−−−>| (object) |  
    +−−−−−−−−−+  +−−−−−−−−−−+ +−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−+ 
         | d:  |−−>|     (Date)     | 
         +−−−−−−−−−−+ +−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−+ 
             | [[TimeValue]]: 2017−03−27T18:00:00+01:00 | 
             +−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−+ 

あなた

let nextTime = moment(res[res.length - 1]).add(1, 'hour'); 
// ... 
res.push(nextTime); 

修正をしてresの上にそれを別の参照プッシュ：だから、あなたはこれで始めると言う

 
    +−−−−−−−−−+   
res−>| (array) |   
    +−−−−−−−−−+  +−−−−−−−−−−+ 
    | 0  |−−−−+−−>| (object) | 
    | 1  |−−−/ +−−−−−−−−−−+ +−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−+ 
    +−−−−−−−−−+  | d:  |−−>|     (Date)     | 
         +−−−−−−−−−−+ +−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−+ 
             | [[TimeValue]]: 2017−03−27T19:00:00+01:00 | 
             +−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−+ 

お知らせをどのようにオブジェクトの状態（ [MomentJSオブジェクトで使用されているDateの[[TimeValue]]）が変更されました。あなたは再びそれを行う場合

、私たちは再びそれを更新します。

 
    +−−−−−−−−−+   
res−>| (array) |   
    +−−−−−−−−−+  +−−−−−−−−−−+ 
    | 0  |−−−−+−−>| (object) | 
    | 1  |−−−/ +−−−−−−−−−−+ +−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−+ 
    | 2  |−−/  | d:  |−−>|     (Date)     | 
    +−−−−−−−−−+  +−−−−−−−−−−+ +−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−+ 
             | [[TimeValue]]: 2017−03−27T20:00:00+01:00 | 
             +−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−+ 

は代わりに、新しいオブジェクトを作成します。オリジナルのクローンをmomentとすることで、これを行うことができます。

let nextTime = moment(res[res.length - 1]).add(1, 'hour'); 
// ------------^^^^^^^ ----------------^ 
// ... 
res.push(nextTime); 

あなたがそれを行う場合は、同じ出発点から、我々が得る：

 
    +−−−−−−−−−+   
res−>| (array) |   
    +−−−−−−−−−+  +−−−−−−−−−−+ 
    | 0  |−−−−−−−>| (object) | 
    | 1  |−−−−+ +−−−−−−−−−−+ +−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−+ 
    | 2  |−−+ | | d:  |−−>|     (Date)     | 
    +−−−−−−−−−+ | | +−−−−−−−−−−+ +−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−+ 
        | |     | [[TimeValue]]: 2017−03−27T18:00:00+01:00 | 
        | | +−−−−−−−−−−+ +−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−+ 
        | +−−>| (object) |             
        |  +−−−−−−−−−−+ +−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−+ 
        |  | d:  |−−>|     (Date)     | 
        |  +−−−−−−−−−−+ +−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−+ 
        +−−−−>    | [[TimeValue]]: 2017−03−27T19:00:00+01:00 | 
         +−−−−−−−−−−+ +−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−+ 
         | (object) |             
         +−−−−−−−−−−+ +−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−+ 
         | d:  |−−>|     (Date)     | 
         +−−−−−−−−−−+ +−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−+ 
             | [[TimeValue]]: 2017−03−27T20:00:00+01:00 | 
             +−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−+