Generators in Javascript into the new ECMA standard

Question

Generators are being introduced in the new version of the ECMA standards. Could any one suggest the importance and the usage of generators in the present Javascript world? Examples of generators in real world problems will be helpful.

Answer 1

Starters

I'd suggest to look at:

• the ECMAScript Harmony Project's wiki page on Generators,
• the Mozilla Developer Doc on Iterators and Generators,
• the JavaScript Tips page of the jslibs project,
• the Google Traceur Compiler's page on JavaScript Language Features,
• SO questions for "javascript generator yield".

A simple example is given in the Mozilla Developer Doc introducing the new features of JavaScript 1.7:

function fib() {
  var i = 0, j = 1;
  while (true) {
    yield i;
    var t = i;
    i = j;
    j += t;
  }
}

var g = fib();
for (var i = 0; i < 10; i++) {
  console.log(g.next());
}

Others are available in the documents listed above.

Real-World

For real world examples, you can for instance see:

• Google's own Traceur-Compiler's tests for EndYieldGenerator, and SwitchGenerator,
• or even the whole test battery for the yield keyword in Google's traceur-compiler,
• or the AcidMonkey tests, for instance this Pi Generator.

Answer 2

I think Generators are best explained in the following article: https://developer.mozilla.org/en/JavaScript/Guide/Iterators_and_Generators

This might be also useful: http://ejohn.org/blog/javascript-18-progress/