Javascript写if语句提示用户输入

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.");
}

所以主要的想法是让用户输入一个单词。 由于某种原因，它标记布尔值为false并直接进入else语句.....

Answer 1

这是因为isNaN（＆＃34;某些文字＆＃34;）返回一个布尔值true / false - 和true ==＆＃34; True＆＃34;返回false。您的陈述应为：

$(function() {
  $('#user').keyup(function(e) {
    var $items = $('#item li');

    var val = this.value;

    var $newItems = $items.each(function(i, item) {

      if (!val || $(item).text().indexOf(val) === -1) {
        $(item).addClass('hidden');
      } else {
        $(item).removeClass('hidden');
      }
    })

  });

});