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javascriptgeneratoriterable

Get the generator function's name from a generator

In Javascript, given a generator object, how do I get it to output the name of the generator function that returned back that generator object?

In other words:

function* thisIsMyName(i) {
  yield i;
}

const gen = thisIsMyName(10);

console.log(gen.name); // How do I get this to output "thisIsMyName" using only the gen object?

Calling gen.name doesn't work as it isn't a function but a generator object

Solution

  • I am afraid you cannot access it like that because the reference to the function that generated this generator is stored in a property defined by a symbol. Symbols are unique and cannot be recreated (but nut all the time, see Symbol.for). Meaning that if you don't have the reference to a symbol you cannot get its value.

    Object.getOwnPropertySymbols() does not return the native ones.

    You can see however the symbol props in the console when inspecting the instance:

    Console

    You can solve this however with a wrapper function, meaning a function that will return both the generator and the generator function:

    function thisIsMyName(value){
  const generatorFunction = function* thisIsMyName(i) {
    yield i;
  }
  return {
    generator : generatorFunction(value),
    generatorFunction: generatorFunction
  }
}
const gen = thisIsMyName(10);

console.log(gen.generatorFunction.name) // prints thisIsMyName
console.log(gen.generator.next()) // prints {value: 10, done: false}