What causes the custom function to yield both accurate outcomes and undefined results?

Recently, I've been honing my JavaScript skills and decided to test them with the following code snippet:

var Intel = ["a", "v", "f", "c", "s"];

if (Intel && Intel.constructor == Array) {
    alert('correct');
} else {
    alert("false");
}

alert(Intel.length);

function showThemAll() {
    // this function will display every item in the array

    for (var i = 0; i <= Intel.length; i++) {
        // alert each item in the array
        alert(Intel[i]);

    }

}

showThemAll();

Despite getting the correct result, I'm puzzled by an 'undefined' alert that pops up. Can anyone shed some light on this issue?

Answer №1

while (i <= Intel.length) 

Remember, arrays start at index zero, so make sure to adjust your loop accordingly

To avoid any undefined errors, modify your code like this:

for (var i = 0; i < Intel.length; i++) {

Answer №2

Running the loop until i <= Intel.length may cause an off-by-one error.

The correct condition should be i < Intel.length

Remember, array indexes start at 0 and go up to one less than the length of the array.

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