Question

我正在尝试创建一个只占一个字母的表单，并在数组中找到它的位置（基本上是字母表）。

我写了一些这个简单的代码：

var alphabet = ["a","b","c","d","e","f","g","h","i","j","k","l","m","n","o","p","q","r","s","t","u","v","w","x","y","z"];
var letter = "h";
var letterPosition = alphabet.indexOf(letter);

document.write(letterPosition);

演示基本功能。但是，我不确定如何将其放入function get并使var letter等于表单输入中的值。

我想让它返回数组中的位置，以便我可以编写一个循环（在if / else中），它将打印输入值之后的数组中的所有值。

Answer 1

构建演示 http://jsbin.com/ijuco4

Answer 2

尝试：alphabet[alphabet.indexOf(letter)]或代码alphabet[letterPosition]

关于您提到的循环：使用该值，您可以使用slice方法为您提供alphabet数组中剩余字符的子集（ergo：不需要）用于确定数组中元素的其余部分的循环：

var subset = alphabet.slice(indexOf([a letter]));

只是为了节省一些打字：你也可以像这样声明你的字母数组：

var alphabet 'abcdefghijklmnopqrstuvwxyz'.split('');

Answer 3

不确定上下文，是否加载了页面（不涉及AJAX）？我可能过于简单了：

<input type="text" id="whichLetter" />
<script type="text/javascript">

function getLetterPosition(allLetters, letter)
{
  return allLetters.indexOf(letter);
}

var alphabet = ["a","b","c","d","e","f","g","h","i","j","k","l","m","n","o","p","q","r","s","t","u","v","w","x","y","z"];
var letter = document.getElementById("whichLetter").value;
var letterPosition = getLetterPosition(alphabet, letter);

</script>

我喜欢javascript。

Answer 4

或者你可以做到

let alphabetPosition = (text) => text.toUpperCase().replace(/[^A-Z]/g, '').split('').map(ch => ch.charCodeAt(0) - 64).join(' ');

用于在javascript数组中查找值的位置的表单

4 个答案: