Javascript 对象构造函数数组未按预期工作

Question

我正在创建一个 Employee 对象类型的数组，但其中一个属性未按预期工作。

我正在使用 Employee 类型的对象数组，该数组是通过构造函数语句 block 定义的。构造函数的一部分是，如果没有定义昵称属性，则使用名字作为昵称。另外，如果未定义移位，则将其设置为“1”。

当我调试时，我发现昵称和类次总是设置为好像没有为这些属性定义任何内容，即使它们是这样。给出了什么？

详细信息:在Win7机器上运行在IE9上，也使用jquery2.1。

代码如下:

// make sure doc ready first
$(document).ready(function(){
    function Employee(firstname, lastname, nickname, employeeID, shift, serviceTruck, pickupTruck, serviceTruckWO){
        this.firstname = firstname;
        this.lastname = lastname;
        /*
         * Check if the nickname is present. If not,
         * set as lastname. Credit to SO for
         * how to do this properly, ref
         * http://stackoverflow.com/questions/27509/detecting-an-undefined-object-property-in-javascript
         */
        if (typeof this.nickname === "undefined") {
            this.nickname = this.firstname;
        }
        else {
            this.nickname = nickname;
        }
        this.employeeID = employeeID;
        if (typeof this.shift === "undefined") {
            this.shift = "1";
        }
        else {
            this.shift = shift;
        }
        this.serviceTruck = serviceTruck;
        this.pickupTruck = pickupTruck;
        this.serviceTruckWO = serviceTruckWO;
    }
    var Employees = new Array();
    Employees[0] = new Employee("John", "Smith", "Smithy", "1234", "2", "ST1", "PU1", "WO1");
    Employees[1] = new Employee("Jane", "Doe", "", "1235", "", "ST2", "PU2", "WO2");

});

Answer 1

您在设置 this.nickname 之前检查它，因此它的类型仍然未定义。

if (typeof nickname === "undefined") {
        this.nickname = this.firstname;
    }
    else {
        this.nickname = nickname;
    }