# Repl(自訂命令列)

全名為Read-Eval-Print-Loop (REPL)

主要用來產生一個terminal終端機程式，可接受使用者從終端機的輸入做對應的輸出，或是直接將想顯示的文字輸出至終端機

一開始我們先開啟terminal，然後輸入node，進入node.js命令列

之後輸入`.help`

1.試著輸入`.editor`

然後打上如下程式

```
function welcome() {
  return `Hello!`;
}

welcome();
```

接著按下鍵盤的ctrl + D

即可看到Hello出現在terminal上

2.試著輸入 `.save ./test2.js`

發現剛才的程式存成檔案

3.再來可輸入 `.load ./test2.js` 可用來讀取並執行一個js檔案

4.點選鍵盤左上的`tab`按鈕可列出所有變數

5.試著輸入`fs.createReadStream('./test2.js');`

最後輸入兩次ctrl + C 即可退出nodejs命令列


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