How to Export Query in Power BI Desktop as CSV

PattemManohar This is an old thread and not what the OP was looking for, but there are a bunch of ways to export the M-code:

• Just select and copy the query or queries from the list of queries in Excel or Power BI Desktop and paste them anywhere. You don't have to open the Advanced Editor. It really is that simple. You can even paste directly into another Excel or Power BI Desktop file. If you paste them somewhere for documentation purposes (eg. Word, OneNote, Notepad, etc.), the formatting is quite a bit different depending on where you paste them. I prefer the format when you paste into Notepad because it is more readable.
• In Excel, you can export queries via VBA macros. Here is the one I use: 

Sub GetAllQueries()
'This will get all Power Query queries in this workbook and save them to a sheet named "PowerQuery".
'This will attempt to delete the sheet first and then create it

    Dim q As Queries
    Dim i As Integer
    Dim s As Worksheet
    
    'Delete sheet named "PowerQuery" if it exists
    On Error Resume Next 'turn off error checking
    Application.DisplayAlerts = False
    ActiveWorkbook.Sheets("PowerQuery").Select
    ActiveWorkbook.Sheets("PowerQuery").Delete
    Application.DisplayAlerts = True
    On Error GoTo 0  'turn error checking back on
    
    'Add sheet named "PowerQuery"
    Set s = ActiveWorkbook.Sheets.Add()
    s.Name = "PowerQuery"
    
    'Loop through all queries and add them to the "PowerQuery" sheet
    'Column A = Query name, Column B = Query "formula" (the query itself", Column C = Query description (Often blank. You can set desc from the All Properties button on the Query Settings pane.)
    Application.ScreenUpdating = True
    For i = 1 To ActiveWorkbook.Queries.Count
        'Show progress on the status bar (lower left corner)
        'If there are a lot of queries, this helps show progress
        Application.StatusBar = "Fetching query " & i & " of " & ActiveWorkbook.Queries.Count
        DoEvents                 'Without this, the Status Bar updates won't show
        
        'Write query info to sheet, leave top row blank (i+1) for headers
        s.Cells(i + 1, 1).Value = ActiveWorkbook.Queries(i).Name          'Column A (1)
        s.Cells(i + 1, 2).Value = ActiveWorkbook.Queries(i).Formula       'Column B (2)
        s.Cells(i + 1, 3).Value = ActiveWorkbook.Queries(i).Description   'Column C (3)
    Next
    'Clear status bar
    Application.StatusBar = False
    
    'Format the sheet
    'Resize columns
    s.Columns("A:A").EntireColumn.AutoFit
    If s.Columns("A:A").ColumnWidth < 28 Then s.Columns("A:A").ColumnWidth = 28
    s.Columns("B:C").ColumnWidth = 80
    
    'Align & wrap text
    s.Columns("A:C").Select
    With Selection
        .VerticalAlignment = xlTop
        .WrapText = True
    End With
    
    'Add headers
    s.Range("A1").Value = "Query name"
    s.Range("B1").Value = "Formula"
    s.Range("C1").Value = "Description"
    Range("B2").Select
    ActiveWindow.FreezePanes = True
    
    'Add refresh button
    ActiveSheet.Shapes.AddShape(msoShapeRoundedRectangle, 80, 0, 60, 15).Select
    Selection.ShapeRange(1).TextFrame2.TextRange.Characters.Text = "Refresh"
    With Selection.ShapeRange(1).TextFrame2.TextRange.Characters(1, 7).Font
        .Fill.ForeColor.RGB = RGB(0, 0, 0)
        .Size = 11
    End With
    With Selection.ShapeRange.Fill
        .ForeColor.ObjectThemeColor = msoThemeColorAccent4
    End With
    With Selection.ShapeRange.TextFrame2
        .TextRange.ParagraphFormat.Alignment = msoAlignCenter
        .VerticalAnchor = msoAnchorMiddle
        .TextRange.Font.Bold = msoTrue
    End With
    Selection.OnAction = "GetAllQueries"
    
    'Add table
    ActiveSheet.ListObjects.Add(xlSrcRange, Range("$A$1", Cells.SpecialCells(xlCellTypeLastCell)), , xlYes).Name = "PowerQueries"
    Range("A1").Select
    
End Sub

•  For Power BI Desktop, use DAX Studio with the following query:

select [Name], [Expression], [Description], [ModifiedTime] from $SYSTEM.TMSCHEMA_EXPRESSIONS

 Then like the other answer in this thread, you can export the result to a file.