Load javascript file in body

The user sees content loading, so the page looks responsive. At this point, the heavy javascripts can begin loading near the end. Only core files that are absolutely needed in the beginning of the page load should be there. The rest, like cool menu effects, transitions, etc.

You want the page to appear responsive i. An AJAX pattern is to load javascript dynamically , or when the user runs a feature that requires your script.

You can load an arbitrary javascript file from any domain using the following import function :. There is an AJAX version as well but I prefer this one because it is simpler and works for files in any domain. Rather than loading your javascript on-demand which can cause a noticeable gap , load your script in the background, after a delay.

Use something like. You can even have a function at the end of these imported files that does whatever initialization is needed or calls an existing function to do the initialization. Rename myfile. Be careful with using this for your own files, especially if they are under development. Because the filename is different, the browser will request a new version. A great method I initially forgot is merging several javascript files into one.

Your browser can only have so many connections to a website open at a time — given the overhead to set up each connection, it makes sense to combine several small scripts into a larger one. Use a script to merge the files — check out part 2 for an example script to do this. You probably should. I originally said no, because some older browsers have problems with compressed content. But the web is moving forward.

Here are some additional references to dive in deeper:. JavaScript onload: Main Tips 2. Learn Event Syntax 4. Code Examples: Best Practice. Example Copy. Try it Live Learn on Udacity. Pros Simplistic design no unnecessary information High-quality courses even the free ones Variety of features. Nanodegree programs Suitable for enterprises Paid certificates of completion. Pros Easy to navigate No technical issues Seems to care about its users.

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Free certificates of completion Focused on data science skills Flexible learning timetable. Previous Topic Next Topic. JavaScript CheatSheets of Functions. JavaScript Syntax. JS interop calls are asynchronous by default, regardless of whether the called code is synchronous or asynchronous.

Calls are asynchronous by default to ensure that components are compatible across both Blazor hosting models, Blazor Server and Blazor WebAssembly.

On Blazor Server, JS interop calls must be asynchronous because they're sent over a network connection. For apps that exclusively adopt the Blazor WebAssembly hosting model, synchronous JS interop calls are supported.

For more information, see ASP. NET Core Blazor performance best practices. JavaScript JS initializers execute logic before and after a Blazor app loads. JS initializers are useful in the following scenarios:. JS initializers are detected as part of the build process and imported automatically in Blazor apps. Use of JS initializers often removes the need to manually trigger script functions from the app when using Razor class libraries RCLs.

Place the file in the project's web root, which is typically the wwwroot folder. The following example demonstrates JS initializers for beforeStart and afterStarted. For the filename of the following example:. However, developer code can include a script to fetch the app's manifest and trigger the load of the JS initializers. Documentation links to the ASP. NET Core reference source load the repository's main branch, which represents the product unit's current development for the next release of ASP.

NET Core. To select the branch for a different release, use the Switch branches or tags dropdown list to select the branch. NET Core 6. These approaches pollute the client with global functions. For production apps, we recommend placing JavaScript into separate JavaScript modules that can be imported when needed.

For more information, see the JavaScript isolation in JavaScript modules section. Collocation of JavaScript JS files for pages, views, and Razor components is a convenient way to organize scripts in an app.

When the external JS file is supplied by a Razor class library , specify the JS file using its stable static web asset path:. For more information, see Consume ASP.