延迟对对象的函数调用

Question

我正在尝试让此代码返回每个员工的姓名。

var company = {
    employees: [
        {
            name: "doug"
        },
        {
            name: "AJ"
        }
    ],
    getName: function(employee){
        return employee.name
    },
    getNames: function(){
        return this.employees.map(this.getName)
    },
    delayedGetNames: function(){
        setTimeout(this.getNames,500)
    }
}

console.log(company.delayedGetNames());

但是，当我运行代码时，我得到“TypeError: Cannot read property 'map' of undefined”

我试过了

setTimeout(this.getNames.bind(this),500)

我只是得到未定义的返回给我。

谁能帮帮我？

Answer 1

用很少的技巧和getters

var company = {
    employees: [
        {
            name: "doug"
        },
        {
            name: "AJ"
        }
    ],
    getName: function(employee){
        return employee.name
    },
    get getNames(){
        console.log(this.employees.map(x => this.getName(x)));
    },
    get delayedGetNames(){
        setTimeout(this.getNames,500)
    }
}

console.log(company.delayedGetNames);

Answer 2

您需要向函数添加回调才能获取名称。

var company = {
    employees: [
        {
            name: "doug"
        },
        {
            name: "AJ"
        }
    ],
    getName: function(employee){
        return employee.name
    },
    getNames: function(){
        return this.employees.map(this.getName)
    },
    delayedGetNames: function(cb){
        setTimeout(()=>cb(this.getNames()),500)
    }
}
company.delayedGetNames(names => console.log(names))

Answer 3

或者，使用Promise，你可以这样写：

var company = {
    employees: [
        {
            name: "doug"
        },
        {
            name: "AJ"
        }
    ],
    getName: function(employee){
        return employee.name
    },
    getNames: function(){
        return this.employees.map(this.getName)
    },
    delayedGetNames: function() {
        return new Promise(resolve => setTimeout(() => resolve(this.getNames()), 1000));
    }
}

company.delayedGetNames().then(console.log);