如何在JavaScript中使用“ +”

Question

当我在#weeksinayear中输入1，在#leaveweeks中输入2时，我得到了12的答案，这是错误的。有什么帮助吗？当我在#weeksinayear输入30或在#leaveweeks输入10时，我将得到3010的答案。

<input type='text' id='weeksinayear'/>
<input type='text' id='leaveweeks'/>
<input type='text' id='totalweeksperyear'/>

$(document).ready(function(){

  $("#weeksinayear").keyup(function(){

        var weeksinayear = $("#weeksinayear").val();
        var leaveweeks = $("#leaveweeks").val();

      if(weeksinayear == ""){
                  var totalweeksperyear = $("#totalweeksperyear").val("");

      }else if(leaveweeks == ""){

                  var totalweeksperyear = $("#totalweeksperyear").val("");

      }else{

          var cal =  (weeksinayear) + (leaveweeks);

          var totalweeksperyear = $("#totalweeksperyear").val(cal);

      }


});
});

Answer 1

使用parseInt（）

将行更改为此

var totalweeksperyear = $("#totalweeksperyear").val(parseInt(weeksinayear,10) + parseInt(leaveweeks,10));