Question

我正在尝试编写一个函数，该函数将验证逗号中的所有条目是否为数字并显示＆＃34;？＆＃34;如果他们不是。例如：用户输入2,3,5b，c7我得到的输出是BCE？而不是BC？这是我试图验证的解码函数：

function fnDecode() {
    var msg = $("textin").value;
        if(msg === "") {
        $("textin_span").innerHTML = "* Please enter a value to decode 
              *";
        $("textin").focus();
    return;
    } else {
        $("textin_span").innerHTML = "";
    }
    var nums = msg.split(","); //split method separates by delimiter
    var outstr = ""; //out string

    for (var i=0; i<nums.length; i++) {
        var n2 = parseInt(nums[i]);
        if (isNaN(n2)) { //if isNaN true, print ?

        outstr += "?";
        } else if (isNallN(nums[i])) { //THIS IS WHERE THE FN GOES
            outstr += "?";

        } else if (n2 === 0) {
            outstr += " ";
        } else if (n2 < 1 || n2 >26) {
            outstr += "?";
        }else {
            outstr += String.fromCharCode(n2+64);
        }
    }
    $("textout").value = outstr;

}

function isNallN(s) {
}

Answer 1

我更正了您的fnDecode功能。

您不需要多个if来检查isNaN，!isNaN('5')和!isNaN(5)一样有效。有关详细信息，请查看此Javascript Equality Table。

在这里，我调整了它的功能，以便使用String 参数并返回所需的String。

function fnDecode(msg) {
  var nums = msg.split(",");
  var outstr = "";

  for (num of nums) {
    if (isNaN(num)) outstr += "?"; //isNaN works on "5" and 5
    else if (+num === 0) outstr += " "; //We use +num to parse the String to an int
    else if (+num < 1 || +num > 26) outstr += "?";
    else outstr += String.fromCharCode(+num + 64);
  }
  return outstr;

}

var test = '1,2,3,4,5f,6r';
console.log(fnDecode(test));

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>

这是一个较短的ES6版本：

function fnDecode(msg) {
  return msg.split(',').map( num => isNaN(num) || (+num < 1 || +num > 26) ? '?' : +num == 0 ? ' ' : String.fromCharCode(+num + 64)).join('');
}

var test = '1,2,3,4,5f,6r';
console.log(fnDecode(test));

字母解码Javascript

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