根据D3 v4 documentation， <Window x:Class="Spinner.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
xmlns:local="clr-namespace:Spinner"
mc:Ignorable="d"
ResizeMode="CanMinimize" SizeToContent="WidthAndHeight" Title="Scroll Spinner">
<Grid>
<Grid.RowDefinitions>
<RowDefinition/>
<RowDefinition/>
</Grid.RowDefinitions>
<!-- The button exists just to have something other than the spinner be the object of focus. -->
<Button Content="Reset" TabIndex="0"/>
<!-- The spinner is just a scroll bar overlaying a text box (same tab indices). -->
<!-- Only the scroll bar is named (in order to get its value); the text box just relfects the scroll bar's value. -->
<TextBox GotFocus="TextBox_GotFocus" Grid.Row="1" Height="{Binding ElementName=SpinnerScr, Path=ActualHeight}" HorizontalAlignment="Stretch" IsReadOnly="True" TabIndex="1" Text="{Binding ElementName=SpinnerScr, Path=Value, StringFormat={}{0:####0}}" TextAlignment="Center"/>
<ScrollBar x:Name="SpinnerScr" Background="Transparent" Focusable="True" Grid.Row="1" Height="20" LostFocus="SpinnerScr_LostFocus" Margin="0,3" Maximum="999" Orientation="Horizontal" SmallChange="1" TabIndex="1" Visibility="Hidden"/>
<x:Code>
<![CDATA[
void SpinnerScr_LostFocus(object sender, RoutedEventArgs e) {
SpinnerScr.Visibility = Visibility.Hidden;
}
void TextBox_GotFocus(object sender, RoutedEventArgs e) {
SpinnerScr.Visibility = Visibility.Visible;
SpinnerScr.Focus();
}
]]>
</x:Code>
</Grid>
</Window>
using System.Windows;
namespace Spinner {
public partial class MainWindow : System.Windows.Window {
public MainWindow() {
InitializeComponent();
}
}
}
的函数语法为data()。
这向我建议selection.data([data[, key]])和data是key的可选参数。但data()总是不是必需参数吗？我知道data是可选的，如果没有指定则默认为数组索引 - 但为什么key参数是可选的，什么是不绑定DOM元素的点？
答案 0 :(得分：2)