我试图在变量中添加条件，然后在 if() 条件中赋值，但它没有按预期工作。

尝试过的可能性:

1)

conditionCheck = (getMonth == undefined || getMonth == "" || getMonth == null 
     || getDay == undefined || getDay == "" || getDay == null 
     || getYear == undefined || getYear == "" || getYear == null )

2)

conditionCheck = getMonth == undefined || getMonth == "" || getMonth == null
     || getDay == undefined || getDay == "" || getDay == null 
     || getYear == undefined || getYear == "" || getYear == null 

3)

conditionCheck = "getMonth == undefined || getMonth == "" || getMonth == null 
     || getDay == undefined || getDay == "" || getDay == null 
     || getYear == undefined || getYear == "" || getYear == null"

但如果我按原样添加，则它可以正常工作。

像这样。 ->

if ( getMonth == undefined || getMonth == "" || getMonth == null 
       || getDay == undefined || getDay == "" || getDay == null 
       || getYear == undefined || getYear == "" || getYear == null ) {
} else {
  ageCalculation();
} 

任何想法/建议？

编辑:

function ageCalculation() {
  getDate = getYear + "-" + getMonth + "-" + getDay;
  dob = new Date(getDate);
  today = new Date();
  age = (today - dob) / (365.25 * 24 * 60 * 60 * 1000);
  if (age < 3 || age == 3 || age > 3 && age < 3.00452422294471007) {
    $('.greater-msg, .less-then-msg').remove();
    $(contentParent).find('.fieldset-wrapper').after('<div class="less-then-msg">Disclaimer: In compliance with EO51,  cannot directly engage with mothers with children aged 0 to 3 years old. All content that you will receive via email will only be regarding your pregnancy. </div>');
  } else if (age > 3) {
    $('.greater-msg, .less-then-msg').remove();
    $(contentParent).find('.fieldset-wrapper').after('<div class="greater-msg">You can also visit to know how you can keep giving your child the 360 advantage.</div>');
  }
  if (age <= -1 || age <= -0 || age == 0 || age == -0) {
    $('.greater-msg, .less-then-msg').remove();
  }
}

谢谢!!

最佳答案

TL;DR; 在 JS 中，检查 variable 是否既不是 null、undefined 也不是 empty 只是由，

if (variable) {
  // 'variable' is not null, undefined or ''.
}

您的第一个 和第二个 条件应该可以正常工作。

Be aware, Date.getMonth() returns 0-based index of the month. And if it just happens that month is January, your condition will no longer work since getMonth is 0 and will turn your conditionCheck to be always true.

Because 0 == "".

至于您的第三个 条件，它是一个字符串，当包含在if 条件中时将始终返回true。

另一种方式，

因此，如果 getMonth、getDay 和 getYear 是 ，那么您要运行 ageCalculation 函数不是 undefined、null 或empty。

所以，而不是 (您当前的代码)

if (getMonth == undefined || getMonth == "" || getMonth == null || getDay == undefined || getDay == "" || getDay == null || getYear == undefined || getYear == "" || getYear == null) {
   // ...
} else {
   ageCalculation();
}

正如我上面所说，为了检查变量是 undefined 还是 null 甚至是 ""(empty)，你可以修改你的代码，

if (getMonth && getDay && getYear) {
   // getMonth, getDay, and getYear are not null, undefined or "".
   ageCalculation();
}
else {
   // Either getMonth, getDay and getYear have a value of null, undefined or "".
}

关于javascript - 一个变量中的 jQuery 多个条件，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/37518032/