An occasional infinite loop
importance: 4
This loop is infinite. It never ends. Why?
let i = 0;
while (i != 10) {
i += 0.2;
}
That’s because i would never equal 10.
Run it to see the real values of i:
let i = 0;
while (i < 11) {
i += 0.2;
if (i > 9.8 && i < 10.2) alert( i );
}
None of them is exactly 10.
Such things happen because of the precision losses when adding fractions like 0.2.
Conclusion: evade equality checks when working with decimal fractions.