How to call javascript function on page load in asp.net

解答1，使用RegisterStartupScript来运行

需要注意的是，下面的demo，显示的是执行某一个函数

Calling JavaScript function on code behind i.e. On Page_Load

ClientScript.RegisterStartupScript(GetType(), "Javascript", "javascript:FUNCTIONNAME(); ", true);

If you have UpdatePanel there then try like this

ScriptManager.RegisterStartupScript(GetType(), "Javascript", "javascript:FUNCTIONNAME(); ", true);

View Blog Article : How to Call javascript function from code behind in asp.net c#

解答2

使用RegisterClientScriptBlock注册onload

或者注册jQuery的ready

JavaScript that executes after page load

解答1

These solutions will work:

<body onload="script();">

document.onload = function ...

or even

window.onload = function ...

Note that the last option is a better way to go since it is unobstrusive and is considered more standard.

解答2

$(window).on("load", function(){ ... });

.ready() works best for me.

$(document).ready(function(){ ... });

.load() will work, but it won't wait till the page is loaded.

jQuery(window).load(function () { ... });

Doesn't work for me, breaks the next-to inline script. I am also using jQuery 3.2.1 along with some other jQuery forks.

To hide my websites loading overlay, I use the following:

<script>

$(window).on("load", function(){

$('.loading-page').delay(3000).fadeOut(250);

});

</script>

ScriptManager.RegisterStartupScript

RegisterStartupScript(Control, Type, String, String, Boolean)

Registers a startup script block for a control that is inside an UpdatePanel by using the ScriptManager control, and adds the script block to the page.

Remarks

You use the RegisterStartupScript method to register a startup script block for a page that is compatible with partial-page rendering and that has no Microsoft Ajax Library dependencies. Startup script blocks that are registered by using this method are sent to the page only when the control that is registering the block is inside an UpdatePanel control that is being updated. To register a startup script block every time that an asynchronous postback occurs, use the RegisterStartupScript(Page, Type, String, String, Boolean) overload of this method.

If you want to register a startup script that does not pertain to partial-page updates, and if you want to register the script only one time during initial page rendering, use the RegisterStartupScript method of the ClientScriptManager class. You can get a reference to the ClientScriptManager object from the ClientScript property of the page.

The script block that is rendered by the RegisterStartupScript method executes when the page finishes loading but before the page's client onload event is raised. Startup script blocks are located at the bottom of the rendered ASP.NET page just before the </form> tag.

Startup script blocks that are registered by using RegisterStartupScript are not guaranteed to be output in the same order in which they are registered. If the order of the startup script blocks is important, use a StringBuilder object to gather the script blocks in a single string, and then register them all as a single startup script.

RegisterStartupScript(Page, Type, String, String, Boolean)

Registers a startup script block for every asynchronous postback with the ScriptManager control and adds the script block to the page.

Remarks

You use this method to register a startup script block that is included every time that an asynchronous postback occurs. To register a script block for a control that is inside an UpdatePanel control so that the script block is registered only when the UpdatePanel control is updated, use the RegisterStartupScript(Control, Type, String, String, Boolean) overload of this method.