无法调用未定义的方法'toLowerCase'

Question

我正试图重构我的js代码，使其更加枯燥，但遇到了这个错误。这是我的代码

function validate_field(e){
    console.log(typeof e);
    $(e).focusout(function(e){
        var price = $(e).val();
        var number = parseInt(price, 10);
        console.log(number)
        if (number < 0)
        {
            $(e).val(0);
        }
    })
}
$(function(){
    validate_field('#price');
})

根据堆栈跟踪错误在这里的某个位置var price = $(e).val();我在这里错过了什么？

Answer 1

尝试

   function validate_field(e){
        console.log(typeof e);
        $(e).focusout(function(ev){
-------------------------------^ here you are redeclaring the e previously passed as selector 
            var price = $(e).val();
            var number = parseInt(price, 10);
            console.log(number)
            if (number < 0)
            {
                $(e).val(0);
            }
        })
    }
    $(function(){
        validate_field('#price');
    })

Answer 2

您正在用函数的e变量干扰e参数。应该是：

function validate_field(s) { // here also ? I have set "s" as parameter, you can set any word you like
    console.log(typeof s); // noticed the difference here?
    $(s).focusout(function(e) { // noticed the difference here?
        var price = $(this).val();
        var number = parseInt(price, 10);
        console.log(number)
        if (number < 0)
        {
            $(e).val(0);
        }
    });
}

您也可以像@dakait那样更改事件参数以进行细微更改。

Answer 3

重新分配变量会导致问题。

function validate_field(field){ // both variable should not be same e & 'e' of inside function
    console.log(typeof e);
    $(field).focusout(function(e){
        var price = $(field).val();
        var number = parseInt(price, 10);
        console.log(number)
        if (number < 0)
        {
            $(field).val(0);
        }
    })
}
$(function(){
    validate_field('#price');
})

或

可以直接使用以下代码，而无需调用脚本中的其他函数

$(function(){
    $('#price').focusout(function(e){
            var price = $(this).val();
            var number = parseInt(price, 10);
            console.log(number)
            if (number < 0)
            {
                $(this).val(0);
            }
        })
});