如何在 JavaScript 中创建可链接的函数？
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How to make chainable function in JavaScript?
提问by daGrevis
Lets imagine function like this:
让我们想象一下这样的函数：
function foo(x) {
x += '+';
return x;
}
Usage of it would be like:
它的用法如下：
var x, y;
x = 'Notepad';
y = foo(x);
console.log(y); // Prints 'Notepad+'.
I'm looking for a way to create function that's chainable with other functions.
我正在寻找一种方法来创建可与其他函数链接的函数。
Imagine usage:
想象一下用法：
var x, y;
x = 'Notepad';
y = x.foo().foo().toUpperCase(); // Prints 'NOTEPAD++'.
console.log(y);
How would I do this?
我该怎么做？
采纳答案by Alex Turpin
Sure, the trick is to return the object once you're done modifying it:
当然，诀窍是在完成修改后返回对象：
String.prototype.foo = function() {
return this + "+";
}
var str = "Notepad";
console.log(str.foo().foo().toUpperCase());
http://jsfiddle.net/Xeon06/vyFek/
http://jsfiddle.net/Xeon06/vyFek/
To make the method available on String, I'm modifying it's prototype. Be careful not to do this on Objectthough, as it can cause problems when enumerating over their properties.
为了使该方法在 上可用String，我正在修改它的原型。但是要小心不要这样做Object，因为它会在枚举它们的属性时导致问题。
回答by Andrey
If I remember correctly, you can use "this" as a context of a function (object it belongs to) and return it to make the function chainable. In other words:
如果我没记错的话，您可以使用“this”作为函数（它所属的对象）的上下文并返回它以使函数可链接。换句话说：
var obj =
{
f1: function() { ...do something...; return this;},
f2: function() { ...do something...; return this;}
}
then you can chain the calls like obj.f1().f2()
然后你可以像这样链接调用 obj.f1().f2()
Keep in mind, you won't be able to achieve what you are expecting by calling obj.f1().toUpperCase() - it will execute f1(), return "this" and will try to call obj.toUpperCase().
请记住，您将无法通过调用 obj.f1().toUpperCase() 来实现您的期望——它将执行 f1()，返回“this”并尝试调用 obj.toUpperCase()。
