JavaScript将原型设置为对象

Question

I'm trying to get the following code to work.

Array.prototype.test = {
    func: function() {
        console.log(this);
        return this;
    }
};

Then when I run the following.

[].test.func();

The problem is the this within that function is the object Array.prototype.test NOT the array that I passed in.

I feel like there has to be way to do this without setting Array.prototype.test to a function and having to call it like so [].test().func(); .

Chai uses this type of syntax quite a bit. So I'm assuming it's possible.

How can I get this to work as I'm expecting it to?

Answer 1

JavaSript doesn't really have a good way to access that.

You could use a getter for test that returns a function with bound methods.

 Object.defineProperty(Array.prototype, 'test', { configurable: true, enumerable: false, get: function() { return { func: function() { console.log(this); return this; }.bind(this) }; } }); [].test.func(); 

But it's pretty convoluted compared to just using .testFunc .

 // Using Object.defineProperty to avoid enumerable prototype properties. Object.defineProperty(Array.prototype, 'testFunc', { configurable: true, enumerable: false, writable: true, value: function() { console.log(this); return this; } }); [].testFunc(); 

See How does the expect().to.be.true work in Chai? to see they do roughly the same thing.