How To Use /deep/ or >>> in Vue.js?

In Vue.js, the `>>>` or `/deep/` combinator is used to target elements within child components when using scoped styles. However, it seems you are encountering issues where the `>>>` combinator is not functioning as expected and is being sent to the browser verbatim.

Here’s a step-by-step guide to address the problem:

1. Check Vue Version

The `>>>` or `/deep/` combinator is supported in Vue.js versions 2.0 and above. Make sure you’re using a compatible version of Vue. You can check your Vue version by running:
npm list vue

2. Verify Webpack Configuration

Ensure your Webpack configuration is properly set up to handle scoped styles. Your current configuration for Vue components looks mostly correct, but you might want to ensure all necessary loaders are included. For Vue 2.x, a typical configuration looks like this:

{
    test: /\.vue$/,
    loader: 'vue-loader',
    options: {
        loaders: {
            scss: 'vue-style-loader!css-loader!sass-loader'
        }
    }
}

If you’re using Vue CLI, the configuration is handled automatically, so you generally don’t need to configure Webpack manually.

3. Use the Correct Combinator

The `>>>` combinator should work in scoped styles, but if you encounter issues, consider using `/deep/` which is another way to achieve the same result. For example:

.autocomplete /deep/ .autocomplete-input {
    /* your styles here */
}

or:

.autocomplete >>> .autocomplete-input {
    /* your styles here */
}

4. Ensure Scoped Styles Are Used Correctly

Ensure you are using the `scoped` attribute correctly in your Vue component. Scoped styles only apply to the current component and use unique data attributes to achieve this:

5. Verify CSS Processing

Sometimes issues arise if CSS isn’t being processed correctly. Check that your CSS loader is working properly. The output CSS should reflect the deep selectors appropriately. If you see the `>>>` selector in the output, it means the loader is not processing it correctly.

6. Update Dependencies

Ensure that all related packages (`vue-loader`, `vue-style-loader`, `css-loader`, etc.) are up-to-date. Compatibility issues can sometimes be resolved by updating these dependencies.

Run:
npm update

7. Check for Conflicts

There might be conflicts with other configurations or plugins. Check your project for any conflicting configurations or plugins that might be affecting the CSS processing.

8. Use Vue CLI for Easier Configuration

If configuring Webpack manually becomes cumbersome, consider using Vue CLI, which automates configuration for many common use cases, including handling scoped styles.