Adding jQuery programmatically to a web form_ASP.NET jQuery Cookbook（Second Edition）-QQ阅读女频幻言网

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Adding jQuery programmatically to a web form

In addition to adding jQuery to web forms using the script block and the ScriptManager control, the code-behind file can also emit the required script code. This recipe will demonstrate how this can be done.

Getting ready

Create an ASP.NET Web Application project by navigating to File | New | Project | ASP.NET Web Application. Select the Empty template. Name the project WebApplicationWithPageLoad (or any other suitable name).
Add a new Web Form to the project and name it Default.aspx.
Add the jQuery library files to the Scripts folder.
From the Solution Explorer tab, navigate to Default.aspx.vb (VB) or Default.aspx.cs (C#), which is the code-behind file for the web form. Open this file.

How to do it…

In the Page_Load event handler of Default.aspx.vb, use the RegisterClientScriptInclude method to generate a script block on the page, as follows:

For VB, the code is as follows:

Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
   Page.ClientScript.RegisterClientScriptInclude("jquery",   Page.ResolveUrl("~/Scripts/jquery-2.1.4.js"))
End Sub

For C#, the code is as follows:

protected void Page_Load(object sender, EventArgs e)
{
   Page.ClientScript.RegisterClientScriptInclude("jquery",   Page.ResolveUrl("~/Scripts/jquery-2.1.4.js"));
}

How it works…

The RegisterClientScriptInclude method requires two parameters: the key and URL. It adds the script block with the path to the jQuery library in the <form> element, as shown in the following screenshot. The Page.ResolveUrl method is used to return a URL relative to the site root:

Since the jQuery library is added to the <form> element, all the jQuery code should be written in the <form> element instead of the <head> element, preferably toward the end of the page before closing the <form> element.