javascript - 属性(property)范围问题？

Question

我尝试从对象内引用 discount_code 属性，但不断收到以下错误。我如何访问discount_code？

错误:

Uncaught TypeError: Cannot call method 'val' of undefined

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 所说，在定义对象之前您无法访问该对象。

您必须将 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()
};

或者只是将 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()
    }
};