funny little ES6 for (let;;) example

alternate.js

// according to my guesses of what is to come in future ES6 specs:
//   the loop should execute five times so the program should print five numbers at the end
//   the fresh-per-iteration x is captured in a closure (that will increment it by 3), 
//     then executed (for side-effects only) in the cond-expr and post-expr.
//     it will never ever modify the outer x thus five loop iterations
(function() {
    let arr = [];
    let fn = null;
    let cnt = 0;
    for (let x = 0; (fn && fn()), x < 5; (fn && fn()), x++) {
        console.log("loop iteration " + ++cnt);
        fn = function() { console.log("incrementing x with value " + x); x += 3 }
        arr.push(function() {
            console.log(x);
        });
    }
    arr.forEach(function(f) { f(); });
})();

kramer.js

// how many iterations?
// arr printout?
(function() {
    let arr = [];
    let fn = null;
    for (let x = 0; (fn && fn()), x < 5; (fn && fn()), x++) {
        console.log("loop iteration");
        fn = function() { x += 1; }
        arr.push(function() {
            console.log(x);
        });
    }
    arr.forEach(function(f) { f(); });
})();

long.js

(function() {
    let arr = [];
    let cnt = 0;
    let fn = null;
    for (let x = 0; (fn = function() { console.log("incrementing x with value " + x); x += 3 }), x < 5; (fn && fn()), x++) {
        console.log("loop iteration " + ++cnt);
        arr.push(function() {
            console.log(x);
        });
    }
    arr.forEach(function(f) { f(); });
})();

short.js

// this should terminate!
(function() {
    let fn = null;
    for (let x = 0; ((!fn && (fn = function() { ++x }))), x < 2; fn()) {
    }
})();

yoyoma.js

// how many iterations?
// arr printout?
(function() {
    let arr = [];
    let fn = null;
    for (let x = 0; x < 5; x++) {
        console.log("loop iteration");
        fn = function() { x += 1; }
        fn(); fn();
        arr.push(function() {
            console.log(x);
        });
    }
    arr.forEach(function(f) { f(); });
})();

alternate.js

"loop iteration 1"
"incrementing x with value 0"
"incrementing x with value 3"
"loop iteration 2"
"incrementing x with value 4"
"incrementing x with value 7"
"4"
"7"

yoyoma.js

The log:

option 1

loop iteration
loop iteration
3
6

option 2

loop iteration
loop iteration
loop iteration
loop iteration
loop iteration
2
3
4
5
6

get rid of that 7 and I agree with you (option 2). :)

Just noticed and removed it! Bad head math =/. But yeah, it makes sense.

linking to https://gist.github.com/olov/6443290 before nap