javascript for (i = 0; i < XXX.length; i++) -> length question

Question

for (m = 0; m < troopsCount.length; m++) {

                //FM_log(7,"i="+i+" m="+m);
                //FM_log(7,"tipoTropaPrioritaria[m] = "+tipoTropaPrioritaria[m]);
                //FM_log(7,"troopsCount[m] = "+troopsCount[m]);
                //FM_log(7,"availableTroops[m] = "+availableTroops[m]);

                if ((tipoTropaPrioritaria[m] == null || tipoTropaPrioritaria[m] == "undefined")
|| (troopsCount[m] == null || troopsCount[m] == "undefined") ||
(availableTroops[m] == null || availableTroops[m] == "undefined")) 
                    return "alternaTropas(): ERRO - tipoTropaPrioritaria[m] || troopsCount[m] || availableTroops[m] null ou undefined";

                if ((parseInt(tipoTropaPrioritaria[m]) != 0) && (parseInt(troopsCount[m]) != 0)) {
                    naoServe = true;
                    break;
                }
                else {
                    if ((parseInt(availableTroops[m])) < (parseInt(troopsCount[m]))) {
                        naoServe = true;
                        break;
                    }
                    else if (m < troopsCount.length) {
                        naoServe = true;
                    }
                    else { //means m >= troopsCount.length
                        naoServe = false;
                    }
                }
}

my question is: the last statement

else { //means m >= troopsCount.length
    naoServe = false;
}

will it ever be evaluated since

for (m = 0; m < troopsCount.length; m++)

???

Answer 1

No, it won't be executed, assuming that m and troopsCount aren't modified in the loop itself (which in this example they don't seem to be).

As I believe you're pointing out, the loop's conditional would prevent the loop from running again if m were greater than or equal to troopsCount.length at the start of the loop.

Answer 2

Nope. It should never happen.

The loop stops immediately once m < troopsCount.length is false. As such, m >= troopsCount.length will never be true inside the loop, unless you change its value inside the loop itself (which you don't, in this sample).

Answer 3

No. The loop is only evaluated as long as m < troopsCount.length. So m will never be >= troopsCount.length as long as you don't modify m or troopsCount.length inside the loop.

Answer 4

let´s assume troopsCount.length = 10

when m = 9 it will execute all the code in the loop right, but when m = 10 it won´t execute anything.

so if I change it this way:

            else {
                if ((parseInt(availableTroops[m])) < (parseInt(troopsCount[m]))) {
                    naoServe = true;
                    break;
                }
                else if (m < (troopsCount.length - 1)) { // troopsCount.length - 1 = 9, m < 9 = m from 0 to 8
                    naoServe = true;
                }
                else { // troopsCount.length = 9
                    naoServe = false;
                }
            }
        }

it would work, right?