javascript - Web浏览器注入(inject)Javascript将焦点设置到第一个输入框

Question

我想注入(inject)一个 JavaScript 以便将焦点设置到第一个输入框。

我当前的代码是这样的:

Me.WebBrowser1.Focus()

Dim i&
Dim JS(100) As String

'The following Javascript-injection ensures, that the first
'found input-element (if there is one) will be focused
' i = i + 1 : JS(i) = "<script>"
i = i + 1 : JS(i) = "var inputElements = document.getElementsByTagName('input');"
i = i + 1 : JS(i) = "for(i=0; i<inputElements.length; i++)"
i = i + 1 : JS(i) = "{"
i = i + 1 : JS(i) = "  if (inputElements[i].type != 'hidden')"
i = i + 1 : JS(i) = "  {"
i = i + 1 : JS(i) = "    if (inputElements[i].disabled == false)"
i = i + 1 : JS(i) = "    {"
'  If uSetFocusToFirstBox Then
i = i + 1 : JS(i) = "      inputElements[i].focus();"
' End If
'If uScrollIntoView Then
i = i + 1 : JS(i) = "      inputElements[i].scrollIntoView(true);"
'End If
i = i + 1 : JS(i) = "      break;"
i = i + 1 : JS(i) = "    }"
i = i + 1 : JS(i) = "  }"
i = i + 1 : JS(i) = "}"

Dim head As HtmlElement = Me.WebBrowser1.Document.GetElementsByTagName("head")(0)
Dim scriptEl As HtmlElement = Me.WebBrowser1.Document.CreateElement("script")
Dim element As IHTMLScriptElement = DirectCast(scriptEl.DomElement, IHTMLScriptElement)
element.text = Join(JS, "")
head.AppendChild(scriptEl)
Me.WebBrowser1.Document.InvokeScript("sayHello")

有人看到我的错误吗？

谢谢!

Answer 1

将焦点设置在第一个文本输入上

选项 1 - 不使用脚本

您不需要将脚本注入(inject)到文档中。您可以处理DocumentCompleted事件并在那里，使用 GetElementByTagName 查找输入元素并找到第一个已启用的 type="text" 输入，然后调用 Focus() ，它还会自动将焦点输入滚动到 View :

Private Sub WebBrowser1_DocumentCompleted(sender As Object, e As WebBrowserDocumentCompletedEventArgs) _
    Handles WebBrowser1.DocumentCompleted

    Dim firstTextBox = Me.WebBrowser1.Document.GetElementsByTagName("input") _
                         .Cast(Of HtmlElement)() _
                         .Where(Function(element)
                                    Return element.GetAttribute("type") = "text" And _
                                           element.Enabled = True
                                End Function) _
                         .FirstOrDefault()

    If (firstTextBox IsNot Nothing) Then
        firstTextBox.Focus()
    End If 
End Sub

选项 2 - 注入(inject)脚本

由于这个原因，您不需要使用脚本，但如果您需要注入(inject)脚本，这里有一个示例。您应该将对 Microsoft.mshtml 的引用添加到项目中并编写这样的代码:

Private Sub WebBrowser1_DocumentCompleted(sender As Object, e As WebBrowserDocumentCompletedEventArgs) _
    Handles WebBrowser1.DocumentCompleted

    Dim scriptText = "var inputElements = document.getElementsByTagName('input');" & _
                     "for(i=0; i<inputElements.length; i++){" & _
                     "  if (inputElements[i].type == 'text' && !inputElements[i].disabled){" & _
                     "      inputElements[i].focus();" & _
                     "      inputElements[i].scrollIntoView(true);" & _
                     "      break;" & _
                     "  }" & _
                     "}"

    Dim head As HtmlElement = Me.WebBrowser1.Document.GetElementsByTagName("head")(0)
    Dim script As HtmlElement = Me.WebBrowser1.Document.CreateElement("script")
    Dim scriptElement As IHTMLScriptElement = DirectCast(script.DomElement, IHTMLScriptElement)
    scriptElement.text = scriptText
    head.AppendChild(script)
End Sub