Coding-Medium-Event-Emitter

The model receives the prompt (and optional system message). The run uses scorer javascript_function_tests with the JSON configuration below. Pass/fail and partial credit are determined entirely by that scorer against the model output; no human grading.

Return JSON only with a string field named code. The code must be dependency-free JavaScript, define the requested function in the top level or module.exports, and include no markdown, imports, require, timers, network, filesystem, eval, or placeholders.

Implement function createEventEmitter(script). The script is a comma-separated string of operations: 'on:EVENT:HANDLER' registers a handler name on an event, 'off:EVENT:HANDLER' unregisters it, 'emit:EVENT' triggers all current handlers for that event. Return an array where each 'emit' operation contributes the count of handlers called, and 'on'/'off' operations contribute null.

Your JSON must look like {"code":"function createEventEmitter(...) { ... }"}.

{
  "function_name": "createEventEmitter",
  "timeout_ms": 100,
  "test_pass_threshold": 1,
  "partial_credit_threshold": 0.5,
  "tests": "[hidden executable tests]"
}