Question

我有一个函数，我们在其中比较值。我使用了两个if else条件，由于某种原因，它不会转到第二个if语句。在这种情况下，Val将是男性或女性。我们正在检查男性或女性的价值观。我们将gender_val视为男性或女性，但不会转到下一个if语句。

var select_male = '';
var select_female = '';
var gender_val ='';
if ($.isNumeric(val)){
    gender_val='';
   }
else{
    gender_val = val.toLowerCase(); 
  }
if (gender_val == 'male' || gender_val == 'm'){
    select_male = 'active';
 }
else if (gender_val == 'female' || gender_val == 'f'){
    select_female = 'active';
 }

这是我的代码..它不会进入if (gender_val == 'male' || gender_val == 'm')语句。有人可以帮我弄这个吗。

Answer 1

让我们考虑您逐行编码，考虑val = "19"：

var select_male = '';
var select_female = '';
var gender_val ='';

这里没有什么不对的。但是我可能会使用某种布尔值而不是空字符串。

if ($.isNumeric(val)) // what is val? if it is a number then of course you will never enter later statements. But for our "19" this is a solid true.
  gender_val='';
else
  gender_val = val.toLowerCase(); 
// lets add here a logging for val you will tell us what you are really receiving in val
console.log(val);

让我们回到条件。此时gender_val为''。

//      false            ||       false      is false
if (gender_val == 'male' || gender_val == 'm')
  select_male = 'active'; // we are not entering here
//      false            ||       false      is false    
else if (gender_val == 'female' || gender_val == 'f')
  select_female = 'active'; // we are not entering here neither

所以我们结束了你的片段。最终结果是：

select_male is ''
select_female is ''
gender_val is ''

如果val在某种程度上：male，Male，m，M等......最终结果将是：

select_male is 'active'
select_female is ''
gender_val is val in lowercase

female，F等的镜面反射...

让我们测试一下：

function test(val) {
  // This is your code, only copied and pasted...
  var select_male = '';
  var select_female = '';
  var gender_val ='';
  if ($.isNumeric(val)) {
    gender_val='';
  }
  else{
    gender_val = val.toLowerCase(); 
  }
  if (gender_val == 'male' || gender_val == 'm') {
    select_male = 'active';
  }
  else if (gender_val == 'female' || gender_val == 'f') {
   select_female = 'active';
  }
  
  console.log([select_male, select_female, gender_val]);
}

// Some test call
test("19");      // Does not work due to $.isNumeric...
test("MaLe");    // Works!
test("f");       // Works!
test("what?");   // Nothing in the gender, is not passing the ifs.
test(undefined); // ooops! Error here!

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

如果由undefined生成toLowerCase输入，请注意错误。

多个if条件在函数

1 个答案: