英文:
Merging a function into an existing object
问题
如果一个已经存在的对象 obj：
const obj = {i: 0,foo(){console.log(this.i)this.i +=1}}obj.foo() // => 0
是否可以将一个函数合并到它里面：
// 应该将以下函数代码添加到 `obj` 中function obj(){this.foo()}// 合并后以下两个函数都应该可用：obj.foo() // => 1obj() // => 2
英文:
If one has an existing object obj:
const obj = {i: 0,foo(){console.log(this.i)this.i +=1}}obj.foo() // => 0
Is it possible to merge a function into it:
// the following function code should be added to `obj`function obj(){this.foo()}// after the merge the following should both work:obj.foo() // => 1obj() // => 2
答案1
得分: 1
我不确定obj函数如何被合并到obj对象中，如果你想要单独调用它的话。然而，你可以使用一个绑定函数来代替。
此外：你不能同时拥有一个名为obj的常量和一个名为obj的函数。因此，我将函数名称更改为fn：
const obj = {i: 0,foo() {console.log(this.i);this.i += 1;}};function fn() {this.foo();}const bound = fn.bind(obj);bound();obj.foo();bound();
编辑
现在我想到了，你不需要fn函数，因为你可以使用const bound = obj.foo.bind(obj); 并且达到完全相同的效果：
const obj = {i: 0,foo() {console.log(this.i);this.i += 1;}};const bound = obj.foo.bind(obj);bound();obj.foo();bound();
英文:
I am not sure how the obj function is merged into the obj object if you want to call it standalone. However, you could use a bound function instead.
Besides: You cannot have a constant obj and a function obj that share the same name. I therefor changed the function name to fn:
<!-- begin snippet: js hide: false console: true babel: false -->
<!-- language: lang-js -->
const obj = {i: 0,foo() {console.log(this.i);this.i += 1;}};function fn() {this.foo();}const bound = fn.bind(obj);bound();obj.foo();bound();
<!-- end snippet -->
EDIT
Now that I think of it, you don't need the fn function since you can use const bound = obj.foo.bind(obj); and achieve exactly the same:
<!-- begin snippet: js hide: false console: true babel: false -->
<!-- language: lang-js -->
const obj = {i: 0,foo() {console.log(this.i);this.i += 1;}};const bound = obj.foo.bind(obj);bound();obj.foo();bound();
<!-- end snippet -->
答案2
得分: 0
使用 Object.assign 可以将函数合并到对象中。我将 obj() 更改为 baz() 以使其更清晰。
const obj = {i: 0,foo() {console.log(this.i);this.i += 1;}};function baz() {this.foo();}Object.assign(obj, { baz });obj.foo() // => 0obj.baz() // => 1
但是，当您调用 baz() 时，它会引发错误，因为它无法理解 baz() 中的上下文 this。因此，您需要使用 obj 作为上下文来调用 baz()
baz.call(obj); // => 2
英文:
You can merge function to object using Object.assign. I changed obj() to baz() to make it more clear.
const obj = {i: 0,foo() {console.log(this.i);this.i += 1;}};function baz() {this.foo();}Object.assign(obj, { baz });obj.foo() // => 0obj.baz() // => 1
However when you call baz(), it will throw error because it doesn't understand the context this in baz(). So you need to call baz() with obj as the context
baz.call(obj); // => 2
答案3
得分: -1
以下是已经翻译好的内容：
有多种方法可以向对象添加属性，如：
- 使用点表示法，
- 使用方括号 [] 表示法，
- 使用 defineProperty()，
- 使用展开运算符，
- 使用 Object.assign()
const obj = {i: 0,foo(){console.log(this.i)this.i +=1}}const newObj = {...obj, obj(){console.log("ok")}}newObj.obj()obj['bar'] = function(){console.log("bar")}obj.bar()
英文:
there are multiple ways to add property to an object like :
1.using dot notation,2.using bracket [ ] notation,3.using defineProperty(),4.using spread operator,5.using Object.assign()
<!-- begin snippet: js hide: false console: true babel: false -->
<!-- language: lang-js -->
const obj = {i: 0,foo(){console.log(this.i)this.i +=1}}const newObj = {...obj, obj(){console.log("ok")}}newObj.obj()obj['bar'] = function(){console.log("bar")}obj.bar()
<!-- end snippet -->
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