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Starter#this binding#Polyfill
Function.prototype.call Polyfill
Implement a Function.prototype.call polyfill from scratch. Master JavaScript this binding, execution context, primitive boxing, and safe property assignment techniques.
By modernDev2025-12-23Medium
The native Function.prototype.call lets you invoke a function with an explicit "this" value and positional arguments. Rebuilding it from scratch forces you to reason about execution context, boxing primitives, and avoiding property collisions.
In this challenge, implement a polyfill that mirrors call's behavior:
- Validate that it is invoked on a function.
- Default null/undefined to the global object.
- Box primitive contexts so "this" is still an object.
- Avoid mutating user properties by using a collision-safe key.
- Clean up temporary state after invocation.
- Return the called function's result.
Goal: Implement Function.prototype.call with correct this handling, primitive boxing, and collision-free temporary storage.
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