What is the purpose of Array.prototype.slice.call (arr, 2) in JavaScript?

Read a lot of JavaScript source code, found a lot of similar wording

2)

It is puzzling that since arr is an array, why not write it directly?

Arr.slice (2)

Why does the instance object itself already have this method, why not call it directly, and use such a notation? Do you have any special intentions?

The main reason is to prevent some objects from having slice methods.

As an example:

In JavaScript, there is a Array-like object, which is like an array, such as having push,slice and so on, with the length property, and you can easily create an object like this:

var foo = {0:' Hello ',1:' world ', Length:2,slice:Array.prototype.slice}    

into an Array object:

Console. log (Array.  Prototype.slice.call (foo,0));    //["World"] console.  Log (Foo.slice ())//["World"]      

This is because this array-like object has this slice method, if not? Can not be used directly, to use the method of the prototype call. As follows:

Console. log (Array.  Prototype. Splice.call (foo,0));    //["World"] console.  Log (foo.  #<object> has no method ' splice '       

Commonly used arguments objects, document.links, document.forms, etc. are very similar to arrays (array), and you can use Array.prototype.slice.call to convert them into a group operation.

Again, consider this example: http://segmentfault.com/q/1010000000774633

What is the purpose of Array.prototype.slice.call (arr, 2) in JavaScript?