ES6 delegating generator

es6-delegating-generator.js

/**
 * ES6 delegating generators.
 * 
 * ES6 dramatically simplified calling of nested generators
 * using "yield *" construct, which is called delegating
 * generator.
 * 
 * From history:
 * Previously (in the original SpiderMonkey/Python) implementation
 * we had to maintain a manual stack for it. The technique was
 * called "trampolining", and basically emulated the call stack:
 * a call to a nested generator had to suspend our execution saving
 * on the stack, run the nested gen, and then restore (pop stack frame).
 * The details of implementation can be found in this diff from 2011:
 * https://gist.github.com/DmitrySoshnikov/1130172
 * 
 * And ES6 did it much, much simpler :) No stacks, no "trampolines",
 * just do the "yield *".
 * 
 * by Dmitry Soshnikov <[email protected]>
 * MIT Style License
 */

function* genScores() {
  yield '-- Score 1';
  yield '-- Score 2';
}

function* genData() {
  yield 'John Doe';
  yield 'Scores:';
  yield* genScores();
  yield 'Completed.';
}

for (var info of genData()) {
  console.log(info);
}

// Output:
// John Doe
// Scores:
// -- Score 1
// -- Score 2
// Completed.

👍 Nice.