我可以得到一些帮助来解决我在 javascript 中的 if else 语句吗？

Question

我一直试图弄清楚我的代码有什么问题，但无济于事。第二列一直显示为未定义，所以我肯定知道这是我在 javascript 中的 if else 语句的问题。如果你能帮助我，那就太好了！<!-- JAVASCRIPT -->var grades = ["70", "69", "100", "95", "60"];{var passed ;if (grades > 69) {    passed = "Passed";} else if (grades <70) {    passed = "Failed";}}document.write('<table>');document.write('<tr><th>Grades</th><th>Passed / Failed</th></tr>'); for (var i = 0; i < grades.length; i++)    {        document.write('<tr><td>' + grades[i] + '</td><td>' + passed + '</td></tr>');    }document.write('</table>')

Answer 1

您必须为每个标记填充通过/失败。您可以使用函数遍历每个标记的逻辑并填充结果

<!-- JAVASCRIPT -->

var grades = ["70", "69", "100", "95", "60"];

  function getpassed(grades){

    var passed;

if (grades > 69) {

    passed = "Passed";

} else if (grades <70) {

    passed = "Failed";

}

    return passed;

}

document.write('<table>');

document.write('<tr><th>Grades</th><th>Passed / Failed</th></tr>'); 

for (var i = 0; i < grades.length; i++)

    {

        document.write('<tr><td>' + grades[i] + '</td><td>' + getpassed(grades[i]) + '</td></tr>');

    }

document.write('</table>')

Answer 2

不应该像现在这样写代码......

尝试这个 ：

var grades = ["70", "69", "100", "95", "60"];

function isPassed(point){

 var passed ;

if (point >= 70) {

    passed = "Passed";

} else if (point <70) {

    passed = "Failed";

}

return passed

}

document.write('<table>');

document.write('<tr><th>Grades</th><th>Passed / Failed</th></tr>'); 

for (var i = 0; i < grades.length; i++)

    {

        document.write('<tr><td>' + grades[i] + '</td><td>' +  isPassed(grades[i]) + '</td></tr>');

    }

document.write('</table>')

Answer 3

grades是一个数组，所以if (grades > 69)和if (grades <70)是没有意义的。

听起来您需要在显示表格时检查每个等级：

for (var i = 0; i < grades.length; i++)

  {

     if ( grades[i] > 69 ) {

       passed = 'Passed'

     } else if ( grades[i] < 70 ) {

       passed = 'Failed'

     }

     document.write('<tr><td>' + grades[i] + '</td><td>' + passed + '</td></tr>');  

  }

Answer 4

首先，您需要迭代grades数组。将 if else 放在for循环中并检查grades[i]而不是整个grades数组。

<!-- JAVASCRIPT -->

var grades = ["70", "69", "100", "95", "60"];

var passed;

document.write('<table>');

document.write('<tr><th>Grades</th><th>Passed / Failed</th></tr>');

for (var i = 0; i < grades.length; i++) {

  if (grades[i] > 69) {

    passed = "Passed";

  } else if (grades[i] < 70) {

    passed = "Failed";

  }

  document.write('<tr><td>' + grades[i] + '</td><td>' + passed + '</td></tr>');

}

document.write('</table>')