一、基础
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Functions/arguments
二、总结
arguments is an Array-like object accessible inside functions that contains the values of the arguments passed to that function.
1）argument in arguments can easily be get、set or reassigned
arguments[0] // first argument
arguments[1] = 'new value';
2）The arguments object is not an Array. It is similar, but lacks all Array properties except length.
3） it can be converted to a real Array: var args = Array.prototype.slice.call(arguments);
4）The typeof operator returns 'object' when used with arguments，The type of individual arguments can be determined by indexing arguments:
三、示例
function func1(a, b, c) { console.log(arguments); console.log(Array.prototype.slice.call(arguments,0)); console.log({length:2,0: 'b',1:'d'}); console.log(Array.prototype.slice.call({length:2,0: 'b',1:'d'})); console.log({0: 'b',1:'d'}); console.log(Array.prototype.slice.call({0: 'b',1:'d'})); } func1(1, 2, 3);
输出
> Object { 0: 1, 1: 2, 2: 3 } //arguments
> Array [1, 2, 3] //arguments can convert to array
> Object { 0: "b", 1: "d", length: 2 } //Array-like object
> Array ["b", "d"] //Array-like object can convert to array
> Object { 0: "b", 1: "d" } //normal object
> Array [] //normal object cannot convert to array
