Implementing Tree-Shaking for a Custom Vue Component

Tree-shaking is a crucial optimization technique that removes unused code from your JavaScript bundles, resulting in smaller file sizes and faster load times. This challenge asks you to implement a simplified form of tree-shaking for a custom Vue component, focusing on conditionally exported functions. By understanding and implementing this, you'll gain a deeper understanding of module bundling and optimization within the Vue ecosystem.

Problem Description

You are tasked with creating a Vue component that conditionally exports utility functions based on a configuration flag. The component itself will be used in a larger application, and you want to ensure that only the functions actually used by the application are included in the final bundle. This is achieved by using a build-time configuration flag that determines which functions are exported.

Specifically, you need to:

1. Create a Vue component named ConditionalComponent.vue.
2. Within ConditionalComponent.vue, define two utility functions: functionA() and functionB(). These functions should simply return strings (e.g., functionA() { return "Function A called"; }).
3. Implement a mechanism to conditionally export these functions based on a build-time configuration flag named INCLUDE_FUNCTION_B. This flag will be a boolean value.
4. The component should not directly use these functions internally. They are intended to be used by the parent component or other modules that import ConditionalComponent.
5. The component should expose a simple template that displays a message indicating which functions (if any) are available. This template should be minimal and primarily serve as a visual confirmation that the component is working.

Expected Behavior:

• Scenario 1: INCLUDE_FUNCTION_B is true: Both functionA and functionB should be exported from ConditionalComponent.vue. A consumer of this component should be able to import and call both functions.
• Scenario 2: INCLUDE_FUNCTION_B is false: Only functionA should be exported. A consumer of this component should only be able to import and call functionA. Attempting to import functionB should result in an error (or undefined value, depending on your implementation).

Edge Cases to Consider:

• What happens if INCLUDE_FUNCTION_B is not defined during the build process? (Default to false is a reasonable approach).
• How will you ensure that the exported functions are actually available to the consumer of the component?
• How will you handle potential errors if a consumer attempts to call an unexported function?

Examples

Example 1: INCLUDE_FUNCTION_B = true

Input: INCLUDE_FUNCTION_B = true
Output:  ConditionalComponent.vue exports both functionA and functionB.
Explanation: The build process includes both functions in the bundle because the configuration flag is set to true.

Example 2: INCLUDE_FUNCTION_B = false

Input: INCLUDE_FUNCTION_B = false
Output: ConditionalComponent.vue exports only functionA.
Explanation: The build process only includes functionA in the bundle because the configuration flag is set to false.  functionB is effectively removed during tree-shaking.

Example 3: INCLUDE_FUNCTION_B is undefined

Input: INCLUDE_FUNCTION_B is not defined
Output: ConditionalComponent.vue exports only functionA.
Explanation: The component defaults to exporting only functionA when the configuration flag is not provided.

Constraints

• Language: TypeScript
• Framework: Vue.js (using the Composition API is preferred, but not required)
• Build Process: Assume a standard Vue CLI project setup with TypeScript. You are responsible for configuring the build process to pass the INCLUDE_FUNCTION_B flag. (You don't need to provide the full Vue CLI configuration, but you should describe how you would do it).
• Performance: The solution should be reasonably efficient. Avoid unnecessary complexity.
• Bundle Size: The goal is to demonstrate tree-shaking, so the difference in bundle size between true and false should be noticeable (though a precise measurement is not required).

Notes

• This challenge focuses on the conditional export aspect of tree-shaking, not the entire bundling process.
• Consider using TypeScript's module system to control exports.
• Think about how you would integrate this solution into a larger Vue project.
• You'll need to describe how you would configure your build process (e.g., using Vue CLI's vue.config.js) to pass the INCLUDE_FUNCTION_B flag. A simple explanation is sufficient; you don't need to provide the complete configuration file.
• The template of the component should be simple, focusing on confirming the presence of the exported functions. It doesn't need to be a complex UI.
• The key is to demonstrate that the build process can conditionally include or exclude code based on a configuration flag, enabling tree-shaking.