underscore.js中_.each方法和_.invoke方法的区别

Question

我无法理解underscore js方法_.each和_.invoke之间的区别。
两者似乎都会在每个项目上调用传递的函数。

在什么情况下应该使用_.each和_.invoke？

请提供一些示例以说明区别。

- Dinesh P.R.

Answer 1

不，它们做不同的事情。看一下它们的代码！

• each calls a given function with each element of a given object. You can additionally pass it a context on which the functions are applied. It acts like the native forEach on arrays.

  iterator.call(context, obj[i], i, obj)
  

  It does return undefined.

• invoke usually gets a method name as a string, and looks up the method dynamically for each element of the given set. Then it applies the method on that element; and you additionally can pass it some arguments.

  (_.isFunction(method) ? method : obj[i][method]).apply(obj[i], args);
  

  It does return the results of the invocations, it basically does map.

- Bergi