Javascript 1.9.3 / ECMAScript 5引入了Object。这是Douglas Crockford等人长期以来一直倡导的。我如何在下面的代码替换新的对象。创建?
var UserA = function(nameParam) {
this.id = MY_GLOBAL.nextId();
this.name = nameParam;
}
UserA.prototype.sayHello = function() {
console.log('Hello '+ this.name);
}
var bob = new UserA('bob');
bob.sayHello();
(假设MY_GLOBAL。nextId存在)。
我能想到的最好的是:
var userB = {
init: function(nameParam) {
this.id = MY_GLOBAL.nextId();
this.name = nameParam;
},
sayHello: function() {
console.log('Hello '+ this.name);
}
};
var bob = Object.create(userB);
bob.init('Bob');
bob.sayHello();
似乎没有任何优势，所以我想我没有得到它。我可能太新古典主义了。我应该如何使用Object。创建创建用户“bob”?
简介:
object. create()是一个Javascript函数，它接受2个参数并返回一个新对象。
第一个参数是一个对象，它将是新创建对象的原型
第二个参数是一个对象，它将是新创建对象的属性
例子:
Const proto = {
Talk: () => console.log('hi')
｝
Const props = {
年龄:{
可写:没错,
可配置:没错,
价值:26
｝
｝
let Person = Object。创建(原型、道具)
console.log (Person.age);
Person.talk ();
实际应用:
The main advantage of creating an object in this manner is that the prototype can be explicitly defined. When using an object literal, or the new keyword you have no control over this (however, you can overwrite them of course).
If we want to have a prototype The new keyword invokes a constructor function. With Object.create() there is no need for invoking or even declaring a constructor function.
It can Basically be a helpful tool when you want create objects in a very dynamic manner. We can make an object factory function which creates objects with different prototypes depending on the arguments received.
我更喜欢结束的方法。
我还在用new。
我不用object。create。
我不用这个。
我仍然使用new，因为我喜欢它的声明性。
考虑简单的继承。
window.Quad = (function() {
function Quad() {
const wheels = 4;
const drivingWheels = 2;
let motorSize = 0;
function setMotorSize(_) {
motorSize = _;
}
function getMotorSize() {
return motorSize;
}
function getWheelCount() {
return wheels;
}
function getDrivingWheelCount() {
return drivingWheels;
}
return Object.freeze({
getWheelCount,
getDrivingWheelCount,
getMotorSize,
setMotorSize
});
}
return Object.freeze(Quad);
})();
window.Car4wd = (function() {
function Car4wd() {
const quad = new Quad();
const spareWheels = 1;
const extraDrivingWheels = 2;
function getSpareWheelCount() {
return spareWheels;
}
function getDrivingWheelCount() {
return quad.getDrivingWheelCount() + extraDrivingWheels;
}
return Object.freeze(Object.assign({}, quad, {
getSpareWheelCount,
getDrivingWheelCount
}));
}
return Object.freeze(Car4wd);
})();
let myQuad = new Quad();
let myCar = new Car4wd();
console.log(myQuad.getWheelCount()); // 4
console.log(myQuad.getDrivingWheelCount()); // 2
console.log(myCar.getWheelCount()); // 4
console.log(myCar.getDrivingWheelCount()); // 4 - The overridden method is called
console.log(myCar.getSpareWheelCount()); // 1
反馈鼓励。
Object的另一种可能用法。Create是用一种廉价而有效的方式克隆不可变对象。
var anObj = {
a: "test",
b: "jest"
};
var bObj = Object.create(anObj);
bObj.b = "gone"; // replace an existing (by masking prototype)
bObj.c = "brand"; // add a new to demonstrate it is actually a new obj
// now bObj is {a: test, b: gone, c: brand}
Notes: The above snippet creates a clone of an source object (aka not a reference, as in cObj = aObj). It benefits over the copy-properties method (see 1), in that it does not copy object member properties. Rather it creates another -destination- object with it's prototype set on the source object. Moreover when properties are modified on the dest object, they are created "on the fly", masking the prototype's (src's) properties.This constitutes a fast an effective way of cloning immutable objects.
这里需要注意的是，这适用于创建后不应该修改的源对象(不可变)。如果源对象在创建后被修改，克隆的所有未屏蔽属性也将被修改。
这里(http://jsfiddle.net/y5b5q/1/)(需要对象。创建功能强大的浏览器)。
