Question

为什么这两个代码块会产生不同的结果？第一个代码块似乎返回false，但第二个代码块正常工作。在第一个块中，我甚至打印了所有布尔操作的值，这些操作都是真的，但它仍然返回false。

return
    mm_card_type_flag &&
                    mm_mm_flag &&
                    mm_yyyy_flag &&
                    $('#hdfccc .' + 'card_no').val() == user_selections.mm_hdfccc_details.mm_number &&
                    $('#hdfccc .' + 'cvv_no').val() == user_selections.mm_hdfccc_details.mm_cvv &&
                    $('#hdfccc .' + 'card_name').val() == user_selections.mm_hdfccc_details.mm_name &&
                    $("#hdfccc .ignorebank").prop('checked') == user_selections.mm_hdfccc_details.ignorebank &&
                    $("#hdfccc .password").val() == user_selections.mm_hdfccc_details.password &&
                    $('#hdfccc input[name="acsRadio"]:checked').val() == user_selections.mm_hdfccc_details.radio_val &&
                    $("#hdfcc-secure-pin").val() == user_selections.mm_hdfccc_details.mm_secure_pin &&
                    $("#hdfccc .prevent-toofast-c").prop('checked') == user_selections.mm_hdfccc_details.prevent_too_fast_c;

和

var ret = mm_card_type_flag &&
                    mm_mm_flag &&
                    mm_yyyy_flag &&
                    $('#hdfccc .' + 'card_no').val() == user_selections.mm_hdfccc_details.mm_number &&
                    $('#hdfccc .' + 'cvv_no').val() == user_selections.mm_hdfccc_details.mm_cvv &&
                    $('#hdfccc .' + 'card_name').val() == user_selections.mm_hdfccc_details.mm_name &&
                    $("#hdfccc .ignorebank").prop('checked') == user_selections.mm_hdfccc_details.ignorebank &&
                    $("#hdfccc .password").val() == user_selections.mm_hdfccc_details.password &&
                    $('#hdfccc input[name="acsRadio"]:checked').val() == user_selections.mm_hdfccc_details.radio_val &&
                    $("#hdfcc-secure-pin").val() == user_selections.mm_hdfccc_details.mm_secure_pin &&
                    $("#hdfccc .prevent-toofast-c").prop('checked') == user_selections.mm_hdfccc_details.prevent_too_fast_c;

    return ret;

全功能

function hdfccc_options_iSame()
    {
        var mm_card_type_flag = true;
        var mm_mm_flag = true;
        var mm_yyyy_flag = true;

        if (user_selections.mm_hdfccc_details.mm_card_type)
            {
                mm_card_type_flag = ($('#hdfccc .' + 'card_type').val() == user_selections.mm_hdfccc_details.mm_card_type);
            }

        if (user_selections.mm_hdfccc_details.mm_mm)
            {
                mm_mm_flag = ($('#hdfccc .' + 'card_expiry_mon').val() == user_selections.mm_hdfccc_details.mm_mm);
            }

        if (user_selections.mm_hdfccc_details.mm_yyyy)
            {
                mm_yyyy_flag = ($('#hdfccc .' + 'card_expiry_year').val() == user_selections.mm_hdfccc_details.mm_yyyy);
            }

            console.log

( mm_card_type_flag ,
                mm_mm_flag ,
                mm_yyyy_flag ,
                $('#hdfccc .' + 'card_no').val() == user_selections.mm_hdfccc_details.mm_number ,
                $('#hdfccc .' + 'cvv_no').val() == user_selections.mm_hdfccc_details.mm_cvv ,
                $('#hdfccc .' + 'card_name').val() == user_selections.mm_hdfccc_details.mm_name ,
                $("#hdfccc .ignorebank").prop('checked') == user_selections.mm_hdfccc_details.ignorebank ,
                $("#hdfccc .password").val() == user_selections.mm_hdfccc_details.password ,
                $('#hdfccc input[name="acsRadio"]:checked').val() == user_selections.mm_hdfccc_details.radio_val ,
                $("#hdfcc-secure-pin").val() == user_selections.mm_hdfccc_details.mm_secure_pin ,
                $("#hdfccc .prevent-toofast-c").prop('checked') == user_selections.mm_hdfccc_details.prevent_too_fast_c);


       var ret=
        mm_card_type_flag &&
                mm_mm_flag &&
                mm_yyyy_flag &&
                $('#hdfccc .' + 'card_no').val() == user_selections.mm_hdfccc_details.mm_number &&
                $('#hdfccc .' + 'cvv_no').val() == user_selections.mm_hdfccc_details.mm_cvv &&
                $('#hdfccc .' + 'card_name').val() == user_selections.mm_hdfccc_details.mm_name &&
                $("#hdfccc .ignorebank").prop('checked') == user_selections.mm_hdfccc_details.ignorebank &&
                $("#hdfccc .password").val() == user_selections.mm_hdfccc_details.password &&
                $('#hdfccc input[name="acsRadio"]:checked').val() == user_selections.mm_hdfccc_details.radio_val &&
                $("#hdfcc-secure-pin").val() == user_selections.mm_hdfccc_details.mm_secure_pin &&
                $("#hdfccc .prevent-toofast-c").prop('checked') == user_selections.mm_hdfccc_details.prevent_too_fast_c;


        return ret;

    }

Answer 1

javascript编译器处理

return
    true

as

return ''; // returns ''
 true      // can't be reached!

你可以将比较器分成多行，但在返回后必须立即有一些东西

return true &&
         false  // returns false

两个代码块给出不同的结果

1 个答案: