财产范围问题

Question

我试图从对象内引用discount_code属性，但我一直得到以下错误。如何访问discount_code

错误:

未捕获的类型错误:不能调用未定义的方法'val'

HTML:

<input type="text" name="txt_discount_code" value="12345" />

JS:

var cart = {
    transaction: {},
    discount_code: $('input[name=txt_discount_code]'),
    get_cart_items_params: {
        page: 'checkout',
        s_method: 'get-cart-items',
        txt_discount_code: this.discount_code.val()
        // txt_discount_code: cart.discount_code.val()
    }
};

Answer 1

就像ShankarSangoli说的，你不能在对象定义之前访问它。

你必须把cart的声明分成两部分:

var cart = {
    transaction: {},
    discount_code: $('input[name=txt_discount_code]')
};
cart.get_cart_items_params = {
    page: 'checkout',
    s_method: 'get-cart-items',
    txt_discount_code: cart.discount_code.val()
};

或者直接将discount_code放入变量中:

var $discount_code = $('input[name=txt_discount_code]');
var cart = {
    transaction: {},
    discount_code: $discount_code
    get_cart_items_params = {
        page: 'checkout',
        s_method: 'get-cart-items',
        txt_discount_code: $discount_code.val()
    }
};

Answer 2

在对象完全定义之前不能使用它。

Answer 3

我最初认为你的问题在于你的jQuery选择器，但在我替换了jQuery选择器的静态值，并尝试引用它仍然没有工作。我得出的结论是，在完成对象的创建之前，不能引用discount_code:

查看

var cart = {
    transaction: {},
    get_cart_items_params: {
        page: 'checkout',
        s_method: 'get-cart-items',
        txt_discount_code: function(){
         return $('input[name="txt_discount_code"]').val();
        }
    }
};
cart.get_cart_items_params.txt_discount_code();