const+spillover: A trivial reproduction of what tripped me out with using const within a for loop.

expected.c

#include <stdio.h>
#include <string.h>

int main() {
    char *lang = "c_language";
    size_t len = strlen(lang);

    size_t i;
    for (i = 0; i < len; ++i) {
        const char c = lang[i];
        printf("%c", c);
    }

    return 0;
}

trippy.js

var lang = 'javascript';

for (var i = 0, len = lang.length; i < len; ++i) {
    var c = lang[i];
    console.log(c); // Should iterate through all the letters
}
// Spill over expected
console.log(c); // Expecting lang[i]

for (var i = 0, len = lang.length; i < len; ++i) {
    const c = lang[i];
    console.log(c); // Should always give 'j'
}
// Spill over still expected
console.log(c); // Should give 'j'