遍历数组的更好方法

Question

我对javascript很陌生，有人要求我这样做；任务:根据电影标题和发布日期创建至少由五个对象组成的数组。标题发布日期: Jaws 1975 E.T. 1982心灵1960年IT 1990 Vertigo 1958

然后，创建一个循环，循环遍历数组，在警报框中显示用户输入的一年后发布的电影。例如，如果用户键入‘1978’，那么警报框将只显示E.T.和IT的电影标题。

这是我的方法，但我相信有更好的方法，所以我要求一点帮助！谢谢您:)

movies = ["Vertigo", " Psycho", " Jaws", " E.T", " IT"];
year = ["1958", "1960", "1975", "1982", "1990"];


userInput = prompt("Enter the year of movies you are interested in viewing\nYear: ");
  alert("The year you have selected is " + userInput);

for (movie in movies) {
  if (userInput == year[0]) {
    alert("Here are a list of movies released after; " + userInput);
    alert(movies); 
    break;
  }
  if (userInput == year[1]) {
    alert("Here are a list of movies released after; " + userInput);
    alert(movies[1] + movies[2] + movies[3] + movies[4]); 
    break;
  }
  if (userInput == year[2]) {
    alert("Here are a list of movies released after; " + userInput);
    alert(movies[2], movies[3], movies[4]); 
    break;
  }
  if (userInput == year[3]) {
    alert("Here are a list of movies released after; " + userInput);
    alert(movies[3], movies[4]); 
    break;
  }
  if (userInput == year[4]) {
    alert("Here are a list of movies released after; " + userInput);
    alert(movies[4]); 
    break;
  }
  else {
    alert("There are no movies. Please input the correct information and try again.");
    break;
  }
}
}

Answer 1

基本上，您做了一个硬代码，包装了所有这些年和电影的名称在obj和循环在每个键和值。

movies = {
    1958 : "Vertigo",
    1960 : " Psycho",
    1975 : " Jaws",
    1982 : " E.T",
    1990 : " IT",
}

userInput = prompt("Enter the year of movies you are interested in viewing\nYear: ");
alert("The year you have selected is " + userInput);

Object.entries(movies).forEach(
    ([key, value]) => key < userInput &&  alert("Here are a list of movies released after; " + value));

Answer 2

在不修改数据结构的情况下，这是一个好方法：

首先，根据用户的输入过滤电影：

const filteredYears = year.filter(item => Number(item) >= Number(userInput);

然后得到每一年过滤的电影。

// Loop the filtered years
filteredYears.forEach(year => {
    // Get the index of current element
    const index = year.findIndex(y => y === year);

    // Just in case, if year found
    if ( index !== -1 ){
        alert("Here are a list of movies released after; " + userInput);
        // The movie of this year.
        alert(movies[index]);
    } 
});

Answer 3

试着使用电影的对象：

movies = [
  {
    title:"Vertigo",
    year:1958
  },
   {
    title:"Psycho",
    year:1960
  },
   {
    title:"Jaws",
    year:1975
  }, {
    title:"E.T",
    year:1982
  }, {
    title:"IT",
    year:1990
  }
]

userInput = prompt("Enter the year of movies you are interested in viewing\nYear: ");
alert("The year you have selected is " + userInput);

//filter movies by year from userInput
const selectedMovies=movies.filter((movie)=>movie.year>=parseInt(userInput));

//check if any movie in array
if(selectedMovies.length){
  alert("Here are a list of movies released after: " + userInput);
  //get only movies titles to array
  const moviesTitlesToDisplay=selectedMovies.reduce((list,movie)=> list.concat(movie.title),[]);
  alert(moviesTitlesToDisplay);
} else {
  alert("There are no movies. Please input the correct information and try again.");
}

CodePen示例：https://codepen.io/marcinbzone/pen/popYBaJ