Understanding SPComponentLoader

Oct 13, 2025 by magicalceylontours.com 137 views

Introduction

SharePoint Framework (SPFx) Extensions are a powerful tool for customizing SharePoint pages. One common requirement is to load custom CSS to apply styles to the page. However, when using SPComponentLoader to load custom CSS in SPFx Extensions, it loads after the page has finished loading, resulting in a UI that is not properly styled. In this article, we will explore how to load custom CSS in SPFx Extensions before the page load.

Understanding SPComponentLoader

SPComponentLoader is a utility provided by SPFx that allows you to load components, scripts, and styles dynamically. It is commonly used in SPFx Extensions to load custom components and styles. However, by default, SPComponentLoader loads components and styles after the page has finished loading.

Loading Custom CSS Before Page Load

To load custom CSS before the page load, you can use the executeOrDelayUntilLoaded method provided by SPComponentLoader. This method allows you to execute a function when the page has finished loading, or after a specified delay.

Here is an example of how to use executeOrDelayUntilLoaded to load custom CSS:

import { SPComponentLoader } from '@microsoft/sp-loader';
// Load custom CSS using SPComponentLoader
SPComponentLoader.loadScript(this.context.pageContext.web.absoluteUrl + '/_layouts/15/sp.runtime.min.js')
.then(() => {
SPComponentLoader.loadScript(this.context.pageContext.web.absoluteUrl + '/_layouts/15/sp.runtime.min.js')
.then(() => {
SPComponentLoader.loadCss(this.context.pageContext.web.absoluteUrl + '/_layouts/15/sp.core.min.css')
.then(() => {
// Custom CSS loaded successfully
console.log('Custom CSS loaded successfully');
})
.catch((error) => {
// Custom CSS failed to load
console.log('Custom CSS failed to load');
});
})
.catch((error) => {
// Custom CSS failed to load
console.log('Custom CSS failed to load');
});
})
.catch((error) => {
// Custom CSS failed to load
console.log('Custom CSS failed to load');
});

However, this approach has a limitation. It loads the custom CSS after the page has finished loading, which may not be what you want.

Using `executeOrDelayUntilLoaded` with a Delay

To load custom CSS before the page load, you can use the executeOrDelayUntilLoaded method with a delay. This will execute the function after the specified delay, allowing you to load custom CSS before the page load.

Here is an example of how to use executeOrDelayUntilLoaded with a delay:

import { SPComponentLoader } from '@microsoft/sp-loader';
// Load custom CSS using SPComponentLoader with a delay
SPComponentLoader.executeOrDelayUntilLoaded(this.context.pageContext.web.absoluteUrl + '/_layouts/15/sp.runtime.min.js', () => {
SPComponentLoader.loadCss(this.context.pageContext.web.absoluteUrl + '/_layouts/15/sp.core.min.css')
.then(() => {
// Custom CSS loaded successfully
console.log('Custom CSS loaded successfully');
})
.catch((error) => {
// Custom CSS failed to load
console.log('Custom CSS failed to load');
});
}, 1000); // 1 second delay

In this example, the custom CSS is loaded 1 second before the page load.

Using `executeOrDelayUntilLoaded` with a Promise

Another approach is to use the executeOrDelayUntilLoaded method with a promise. This will execute the function when the promise is resolved, allowing you to load custom CSS before the page load.

Here is an example of how to use executeOrDelayUntilLoaded with a promise:

import { SPComponentLoader } from '@microsoft/sp-loader';
// Load custom CSS using SPComponentLoader with a promise
const loadCustomCss = () => {
return new Promise((resolve, reject) => {
SPComponentLoader.loadCss(this.context.pageContext.web.absoluteUrl + '/_layouts/15/sp.core.min.css')
.then(() => {
// Custom CSS loaded successfully
console.log('Custom CSS loaded successfully');
resolve();
})
.catch((error) => {
// Custom CSS failed to load
console.log('Custom CSS failed to load');
reject(error);
});
});
};
SPComponentLoader.executeOrDelayUntilLoaded(this.context.pageContext.web.absoluteUrl + '/_layouts/15/sp.runtime.min.js', () => {
loadCustomCss();
}, 1000); // 1 second delay

In this example, the custom CSS is loaded 1 second before the page load.

Conclusion

Q: What is the purpose of SPComponentLoader in SPFx Extensions?

A: SPComponentLoader is a utility provided by SPFx that allows you to load components, scripts, and styles dynamically. It is commonly used in SPFx Extensions to load custom components and styles.

Q: Why does custom CSS load after the page has finished loading?

A: By default, SPComponentLoader loads components and styles after the page has finished loading. This is because the page load is a complex process that involves loading multiple resources, and SPComponentLoader waits for the page load to complete before loading custom components and styles.

Q: How can I load custom CSS before the page load?

A: You can use the executeOrDelayUntilLoaded method provided by SPComponentLoader to load custom CSS before the page load. This method allows you to execute a function when the page has finished loading, or after a specified delay.

Q: What is the difference between using `executeOrDelayUntilLoaded` with a delay and using it with a promise?

A: When using executeOrDelayUntilLoaded with a delay, the function is executed after the specified delay, regardless of whether the page has finished loading. When using it with a promise, the function is executed when the promise is resolved, which can be after the page has finished loading or after a specified delay.

Q: Can I use `executeOrDelayUntilLoaded` with a custom function?

A: Yes, you can use executeOrDelayUntilLoaded with a custom function. This allows you to execute a custom function when the page has finished loading, or after a specified delay.

Q: What are the benefits of loading custom CSS before the page load?

A: Loading custom CSS before the page load can improve the user experience by providing a more responsive and visually appealing UI. It can also improve the performance of the page by reducing the time it takes to load custom components and styles.

Q: Are there any limitations to using `executeOrDelayUntilLoaded` to load custom CSS?

A: Yes, there are limitations to using executeOrDelayUntilLoaded to load custom CSS. For example, it can cause issues with page load timing and can lead to unexpected behavior if not used correctly.

Q: Can I use `executeOrDelayUntilLoaded` to load custom scripts and components?

A: Yes, you can use executeOrDelayUntilLoaded to load custom scripts and components. This allows you to load custom scripts and components before the page load, or after a specified delay.

Q: How can I troubleshoot issues with loading custom CSS using `executeOrDelayUntilLoaded`?

A: You can troubleshoot issues with loading custom CSS using executeOrDelayUntilLoaded by checking the console for errors, using the browser's developer tools to inspect the page load, and verifying that the custom CSS is being loaded correctly.

Q: Are there any best practices for using `executeOrDelayUntilLoaded` to load custom CSS?

A: Yes, there are best practices for using executeOrDelayUntilLoaded to load custom CSS. For example, you should use a delay that is short enough to not cause issues with page load timing, and you should verify that the custom CSS is being loaded correctly before the page load.

Conclusion

Loading custom CSS in SPFx Extensions before the page load can be achieved using the executeOrDelayUntilLoaded method provided by SPComponentLoader. By understanding the purpose of SPComponentLoader, the benefits of loading custom CSS before the page load, and the limitations of using executeOrDelayUntilLoaded, you can troubleshoot issues and follow best practices for loading custom CSS in SPFx Extensions.