Replace With Alphabet Position

题目

Welcome.

In this kata you are required to, given a string, replace every letter with its position in the alphabet.

If anything in the text isn’t a letter, ignore it and don’t return it.

“a” = 1, “b” = 2, etc.

Example
alphabetPosition(“The sunset sets at twelve o’ clock.”)
Should return “20 8 5 19 21 14 19 5 20 19 5 20 19 1 20 20 23 5 12 22 5 15 3 12 15 3 11” (as a string)

思路

过滤非字母，全部转换为小写字母之后，将字母转换为ASCII码，减去96就是字母在字母表中的位置。
然后用循环组成最后的字符串。

  • .toLowerCase() 字符串转换为小写字母
  • .trim() 去除字符串首尾空格
  • .charCodeAt() 字符串转换为ASCII码
  • [^a-zA-Z] 非字母的正则式

答案

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function alphabetPosition(text) {
    var rawText = text.replace(/[^a-zA-Z]/g, "").toLowerCase();
    var r_text = "";
    for (i = 0; i < rawText.length; i++) {
        pos = rawText[i].charCodeAt() - 96;
        r_text = r_text + pos.toString() + " ";
    }
    return r_text.trim();
}