如何在jQuery事件绑定中获取“this”

Question

我有一个在keyup或change上调用的函数，但我很难获得this

的值

代码

var myNS = myNS || {};

myNS.validate = {
    dobChange: function(elem){
        console.log($(this).val().length); // trying to check length of "this"
    }
}

$('.dob1-day, .dob1-month, .dob1-year').on('keyup change', myNS.validate.dobChange('foo'));

控制台错误：

Uncaught TypeError: Cannot read property 'toLowerCase' of undefined

如何获取this的价值？

Fiddle

Answer 1

您应该从传递给处理程序的事件中提取DOM元素：

//getting the element
myNS.validate = {
    dobChange: function(e){
        console.log($(e.target).val().length); // trying to check length of "this"
    }
}
//calling handler
$('.dob1-day, .dob1-month, .dob1-year').on('keyup change', myNS.validate.dobChange)

Answer 2

{{1}}

Answer 3

您可以使用call()和匿名函数来设置相关上下文并传递额外的参数：

$('.dob1-day').on('keyup change', function(){myNS.validate.dobChange.call(this, "foo")});

-jsFiddle-

Answer 4

var myNS = myNS || {};

myNS.validate = {
    dobChange: function($element){
        console.log($element.val());
  }
}

$(function () {
    $(".content").on('keyup change','.dob1-day', function(){
                        myNS.validate.dobChange($(this));
                    });
});



<div class="content">
    <input type="text" class="dob1-day">
</div>