<script>
function showMovie(age) {
//Exit if checkAge return value is false
if (!checkAge(age)) {
return alert ('Error');
//The return value of checkAge is true
} } else {
alert('movie screening');
}
}
function checkAge(age) {
if (age > 18) {
return true;
} } else {
//Return false if you do not agree
Did you get the consent of your guardian?');
}
}
function init() {
letage = prompt ('Please tell me your age');
showMovie();
}
init();
</script>
If you enter a value that is over 18 years old, you should get a movie screening message right away. I wonder why it is moved to the confirm message of the protection automatic.
javascript if-else
Just a quick look at the doctor's code:
call showMove()
call checkAge(age) // from here, age is undefined
Ifage > 18 //age is undefined and undefined is NaN, so it must be false
Did you get the consent of your guardian?')
That's what happens.
This is because age is not a global variable, but a regional variable in init(), so it cannot be referenced in other functions.
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