javascript - 如何在 Lo-Dash 中使用 thisArg？

Question

如何在 Lo-Dash 中使用 thisArg？是否可以将它与链接结合起来？这是一个使用其文档中的 thisArg 的示例:

_.map(collection, [callback=identity], [thisArg])

Creates an array of values by running each element in the collection through the callback. The callback is bound to thisArg and invoked with three arguments; (value, index|key, collection).

If a property name is provided for callback the created "_.pluck" style callback will return the property value of the given element.

If an object is provided for callback the created "_.where" style callback will return true for elements that have the properties of the given object, else false.

Aliases

_.collect

Arguments

collection (Array|Object|string): The collection to iterate over.
[callback=identity] (Function|Object|string): The function called per iteration. If a property name or object is provided it will be used to create a ".pluck" or ".where" style callback, respectively.
[thisArg] (*): The this binding of callback.
Returns

(Array): Returns a new array of the results of each callback execution.

我将不胜感激，因为我无法在他们的文档中找到任何示例。

Answer 1

Argument thisArg 只是指向调用者的 this 上下文的指针，它也将用作回调的上下文。它是为了方便而提供的。

结果与使用 native Function.bind() 方法相同，例如:

_.map(collection, callback.bind(this));

另一种方法是创建一个 this 的别名变量并使用它来代替。