Javascript編寫if語句以提示用戶輸入

Question

var noun;
var verb;
var adverb;
var adjective;
var pronoun;
var questions = 5; //this number can adjust
var paragraph;

var noun = prompt("Type Noun");
if (isNaN(noun) == "True"){
 questions -= 1;
 verb = prompt("Type Verb");
}else{
   alert("You entered a number, please enter a Noun.");
}
if (isNaN(verb) == "True"){
 questions -= 1;
 adverb = prompt("Type Adverb");
}else{
   alert("You entered a number, please enter a Verb.");
}
if (isNaN(adverb) == "True"){
 questions -= 1;
 adjective = prompt("Type Adjective");
}else{
   alert("You entered a number, please enter a Adverb.");
}
if (isNaN(pronoun) == "True"){
 questions -= 1;
}else{
   alert("You entered a number, please enter a Pronoun.");
}

因此，主要思想是讓用戶輸入單詞。 由於某種原因，它將布爾值標記為false並直接進入else語句.....

Answer 1

這是因為isNaN（“ some text”）返回布爾值true / false，而true ==“ True”返回false。 您的聲明應為：

if (isNaN(noun) === true) {
}
....