Question

似乎无法找到问题所在。我每次运行它都会获得ageDale的NaN，现在已经看了一会儿，它可能很简单，但我很感激帮助！

<p>Enter names in the fields, then click "Submit" to submit the form:</p>
<form name="form">
    <input type="text" id="birthDate">

    Current Date
    <input type="text" id="currentDate">

    <a id="Submit_Button" onclick="test();" href="javascript:void(0);" title="Submit">Submit</a>
</form>
<script>
    function test() {
        var birthDate   = document.getElementById("birthDate");
        var currentDate = document.getElementById("currentDate");
        var ageDate     = (birthDate.value - currentDate.value);

        if(ageDate.value < 1) {
            (ageDale =  ageDate.value * -1)
        }
        else {
            (ageDale = ageDate.value * 1)
        }

        alert(ageDale)
    }
    </script>

另外，我是否有必要发表其他声明？还是有其他方法来设置它，所以不需要它？

Answer 1

这个

ageDate.value

应该是

ageDate

只。它是一个变量，只包含与

的差异

birthDate.value - currentDate.value

if(ageDate.value < 1) {
         // ^ here
            (ageDale =  ageDate.value * -1)
        }                      //^ here
        else {
            (ageDale = ageDate.value * 1)
                             // ^ and here

您只需从获取数据时获取值，例如输入字段。

另外（取决于您输入它们的方式），计算日期可能会有问题。出于调试目的，你应该

console.log()

您的变量值，这样您就可以快速找到错误的位置。

代码中的console.log（）的好地方就是，例如在这个块之后：

    var birthDate   = document.getElementById("birthDate");
    var currentDate = document.getElementById("currentDate");
    var ageDate     = (birthDate.value - currentDate.value);

    console.log(ageDate);

旁注：

您可能需要查看moment.js，它将帮助您进行日期计算。例如，您可以使用moment.js获取日期之间的差异：

var a = moment([2014, 12, 05]);
var b = moment([2014, 12, 06]);
a.diff(b, 'days') // 1

Answer 2

试试这个：

var btn = document.getElementById("Submit_Button");

btn.onclick = function test() {
    var birthDate   = parseInt(document.getElementById("birthDate").value);
    var currentDate = parseInt(document.getElementById("currentDate").value);
    var ageDate     = (birthDate - currentDate);

    if(ageDate < 1) {
        (ageDate =  ageDate * -1)
    }
    else {
        (ageDate = ageDate * 1)
    }

    alert(ageDate)
}

Answer 3

正如baao所说，你有拼写错误。在纠正这些之后，您需要考虑输入的内容，并确保检查输入是否有效。

例如，如果我输入＆＃34; 9月10日＆＃34;我的生日和＃34; 12月10日＆＃34;对于当前日期，您的函数将尝试减去两个无效的字符串。如果您要在日期中使用自定义输入字段，则需要确保其格式一致且可解析。

我建议以特定格式询问他们的生日并从那里解析，因为我们可以使用Javascript轻松获取当前日期。例如，mm-dd-yy。我们可以将其重写为：

＆＃13;

function test() {

//lets get the date, in the format 'mm-dd-yy'. You'd want to do error checking at some point if you're serious about it
  
var dateInput = document.getElementById("birthDate").value;

//get each individal date type by splitting them at the -, giving ['dd', 'mm', 'yy']
var dateSplit = dateInput.split('-');
   
    //create a Javascript date object with the date we got
    var birthDate = new Date(dateSplit[2], dateSplit[0], dateSplit[1]);
    
    //create another with the current date and time
    var currentDate = new Date();
    
    // find the difference in milliseconds
  
   var dateDifference = Math.abs(birthDate.getTime() - currentDate.getTime());
  
   // convert to years
   var age = dateDifference / (1000 * 3600 * 24 * 365); 
  
  alert(age);

}

＆＃13;

<p>Enter names in the fields, then click "Submit" to submit the form:</p>
<form name="form">
    Birth Date (dd-mm-yy):
  <br>
    <input type="text" id="birthDate">
  <br>
    <a id="Submit_Button" onclick="test();" href="javascript:void(0);" title="Submit">Submit</a>
</form>

＆＃13;

Answer 4

只需修改此代码

    var birthDate   = document.getElementById("birthDate");
    var currentDate = document.getElementById("currentDate");
    var ageDate     = (birthDate.value - currentDate.value);

    if(ageDate.value < 1) {
        (ageDale =  ageDate.value * -1)
    }
    else {
        (ageDale = ageDate.value * 1)
    }

用这个

    var vbirthdate = new Date(document.getElementById("birthDate").value);
    var vcurrentdate = new Date(document.getElementById("currentDate").value);
    var ageDate     = Math.floor((vbirthdate-vcurrentdate)/(1000*60*60*24));

    if(ageDate < 1) {
        (ageDate =  ageDate * -1)
    } // no need to do something like this (ageDate *1) if it is already a positive number, just check if it's a negative then convert it to a positive number

您可以尝试http://jsfiddle.net/kapasaja/duco4cqa/5/

处的代码

你问的是什么类似于this post

Javascript简单的代码错误

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