Why it is returning "false"

Question

var ad=[0]
var per=ad.includes()
while(ad<5){
ad++
}
document.write(per)

Answer 1

line 2: the .includes() function doesn't have a required argument.
It should be like array.includes(element)

Answer 2

Adding to Isaac,
<ad> is an array, and its value can't be compared against a number such as

while( ad < 5 )

And since <ad> was an array, it can't be incremented such as

ad++;